Ch 1 Apomys - Department of Biological Science

Transcription

Chapter 1: Seven New Species and a New Subgenus of Forest Mice (Rodentia:
Muridae: Apomys) from Luzon Island
Author(s): Lawrence R. Heaney, Danilo S. Balete, Eric A. Rickart, Phillip A. Alviola, Mariano Roy M.
Duya, Melizar V. Duya, M. Josefa Veluz, Lawren VandeVrede, and Scott J. Steppan
Source: Fieldiana Life and Earth Sciences, Number 2:1-60. 2011.
Published By: Field Museum of Natural History
DOI: 10.3158/2158-5520-2.1.1
URL: http://www.bioone.org/doi/full/10.3158/2158-5520-2.1.1
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Chapter 1: Seven New Species and a New Subgenus of Forest Mice
(Rodentia: Muridae: Apomys) from Luzon Island
Lawrence R. Heaney1, Danilo S. Balete1, Eric A. Rickart1,2, Phillip A. Alviola1,3,
Mariano Roy M. Duya 4,5, Melizar V. Duya4,5, M. Josefa Veluz6, Lawren VandeVrede7,8,
and Scott J. Steppan7
1
Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605, USA
Utah Museum of Natural History, 1390 East Presidents Circle, Salt Lake City, UT 84112, USA
3
Museum of Natural History, University of the Philippines, Los Baños, Laguna 4031, Philippines
4
Conservation International–Philippines, 6 Maalalahanin Street, Teachers Village, Diliman, Quezon City 1101, Philippines
5
Current address: Institute of Biology, University of the Philippines, Diliman, Quezon City, Philippines
6
National Museum of the Philippines, Rizal Park, Ermita, Manila, Philippines
7
Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
8
Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL 60608, USA
2
Abstract
Surveys of small mammals on carefully selected mountains and mountain ranges on Luzon Island, Philippines, since
2000 have led to the discovery of seven previously unknown species of forest mice, Apomys, a remarkable radiation on
just a portion of one island. On the basis of morphological and cytochrome (cyt) b DNA sequence data presented here,
we propose a new subgenus, Megapomys, to include the large-bodied members of the genus, which form a monophyletic
unit of relatively large mice (averaging ca. 65–110 g) with tails about as long as or slightly shorter than the length of the
head and body; all of these species forage on the ground. Other members of the genus are assigned to the subgenus
Apomys; they are smaller (ca. 18–41 g), have long tails, and usually or often forage above the ground surface. Members
of the subgenus Megapomys include four previously recognized species (A. abrae, A. datae, A. gracilirostris, and A.
sacobianus) and the seven new species described here (A. aurorae, A. banahao, A. brownorum, A. magnus, A minganensis,
A. sierrae, and A. zambalensis). All occur in northern and central Luzon Island, with the exception of one species that
occurs on Mindoro Island; none is present in southern Luzon. Each species can be distinguished both morphologically
and genetically. Although there are few records of Megapomys below 500 m elevation, they are common above about
1000 m, and some species occur near the peaks of the highest mountains on Luzon (i.e., up to nearly 2900 m). On four
mountain ranges, two species of the subgenus co-occur, one at lower and one at higher elevations, although there is
usually some syntopic overlap. Sister-species usually occur allopatrically in different mountain ranges, with one possible
exception. Some of these species occur in areas not previously known to support endemic mammals, indicating that these
areas are previously unrecognized areas of mammalian endemism where further study is warranted.
Introduction
With 23 endemic genera of mammals within a land area of ca.
300,000 km2, the Philippine archipelago has one of the greatest
concentrations of unique mammalian diversity of any place on
earth (Heaney et al., 1998). Foremost among these in diversity
are the murid rodents, with 16 endemic genera and at least 55
endemic species (Heaney et al., 1998; Musser & Carleton, 2005).
Previously unknown murids continue to be described (e.g.,
Rickart et al., 2005; Balete et al., 2006, 2007, 2008; Heaney et
al., 2009), many of them discovered recently as part of a
continuing effort to conduct a comprehensive survey of the
mammals of Luzon Island (e.g., Heaney et al., 1999, 2003; Duya
et al., 2007; Balete et al., 2009; Rickart et al., 2011).
The remarkable diversity within the Philippine Muridae
resides primarily within two endemic lineages: the ‘‘giant cloud
rat lineage’’ (5 Phloeomyini sensu Lecompte et al., 2008), with
five genera and about 15 species (Heaney et al., 1998, 2009;
Jansa et al., 2006), and the ‘‘earthworm-mouse lineage’’ (part
of the Hydromyini sensu Lecompte et al., 2008), with four
genera and 22 species by the latest count (Steppan et al., 2003;
Musser & Carleton, 2005; Jansa et al., 2006; Rowe et al.,
2008). The latter is sister to all Australasian members of
Hydromyini (Rowe et al., 2008; Heaney et al., 2009). The most
speciose genus among these is Apomys Mearns 1905, generally
referred to as Philippine forest mice, with 10 species previously
described and recognized (Steppan et al., 2003; Musser &
Carleton, 2005; Heaney & Tabaranza, 2006). In this paper, we
show that past studies have undersampled, and therefore
greatly underestimated, the number of species in this genus;
herein, we describe seven additional species, all from Luzon.
In doing so, we lay a substantial portion of the groundwork
FIELDIANA: LIFE AND EARTH SCIENCES, NO. 2, May 20, 2011, pp. 1–60
1
FIG. 1. Color drawings of (A) Apomys gracilirostris, (B) A. datae, (C) A. abrae, (D) A. banahao sp. nov., and (E) A. magnus sp. nov. to the
same scale. All drawings by Velizar Simeonovski.
2
FIELDIANA: LIFE AND EARTH SCIENCES
FIG. 2. Color drawings of (A) Apomys zambalensis, (B) A. brownorum, (C and D) A. sierrae (from Mt. Cetaceo and Mt. Palali, respectively),
(E) A. minganensis, and (F) A. aurorae spp. nov., to the same scale. All drawings by Velizar Simeonovski.
HEANEY ET AL.: NEW APOMYS SPECIES AND SUBGENUS
3
phylogeny has revealed the presence of clades that corresponded to those morphological units. In this paper, we describe each
of these morphologically distinct, genetically monophyletic
units as a new species, discuss their patterns of distribution and
phylogeny in the context of the previously described species of
large-bodied Apomys, and consider their distribution patterns
within the complex geography of Luzon Island.
Materials and Methods
Specimens examined and/or referred to in this study are
housed in the following museums, with their standard
acronyms and some ‘‘synonyms’’:
BM(NH)—British
Museum (Natural History) 5 The Natural
History Museum (London)
CMNH—Cincinnati Museum of Natural History, Cincinnati,
OH
FMNH —Field Museum of Natural History, Chicago 5
Chicago Museum of Natural History
NMP—National Museum of the Philippines, Manila
USNM—United States National Museum of Natural History,
Washington, D.C. 5 NMNH
FIG. 3. Map of Luzon and Mindoro, showing mountains and
ranges referred to in the text.
for a detailed examination of the geographic patterns of
mammalian biodiversity on Luzon Island, the largest island in
the Philippines at 102,000 km2, and the site of remarkable
geological and geographical heterogeneity for such limited
area.
Mice of the genus Apomys occur on most of the oceanic
islands of the Philippines, being absent from only three areas:
the Palawan region, which is faunistically more closely
associated with the Sunda Shelf than with the oceanic
Philippines; the Sulu Archipelago, a poorly known but
seemingly species-poor set of islands that lie between Mindanao and Borneo; and the small, isolated islands of the
Batanes and Babuyan groups that lie in deep water north of
Luzon (Musser, 1982; Heaney, 1985, 1986, 2000; Musser &
Heaney, 1992; Steppan et al., 2003; Catibog-Sinha & Heaney,
2006; Heaney et al., 2006a). At many of our sampling
localities, these mice were the most abundant small mammals,
especially at elevations above about 1200 m. As many as four
species can occur on a given mountainside, with up to three
species occurring syntopically. On Luzon, two ecological
groups can be readily identified: small-bodied Apomys that
forage primarily in vegetation (grass, shrubs, and trees) above
the ground, and large-bodied species that forage primarily on
the ground (Musser, 1982; Heaney et al., 1998, 1999, 2003,
2006a,b; Steppan et al., 2003; Balete et al., 2009, this volume;
Alviola et al., this volume; Rickart et al., 2011).
During the 2004–2006 period of the comprehensive survey of
Luzon mammals referred to above, we noted extensive
variation in the external morphology of the large-bodied
Apomys (Figs. 1, 2) that we captured in the northern and
central parts of Luzon (Fig. 3), and we subsequently noted
consistent cranial variation in parallel with the external
morphology. As described below, our mitochondrial gene
4
For muroid taxonomy and nomenclature, we follow Musser
and Carleton (2005) unless otherwise noted.
Heaney examined the holotypes of the following species
(housed at the indicated institutions): Apomys abrae (FMNH),
A. gracilirostris (NMP), A. sacobianus (USNM), and A. major
(USNM). We did not examine the holotype of Apomys datae,
housed at the Staatliches Museum für Tierkunde, Dresden,
Germany; for information on this holotype, we relied on
Musser (1982).
Most of the specimens obtained during and after 2000 were
initially preserved in formalin in the field then rinsed in water
and transferred to ethanol. Many have had their skulls
removed and cleaned by dermestid beetles, followed by soaking
in a dilute ammonia solution, rinsing in water, and picking by
hand. Before fixation with formaldehyde, specimens in the field
had small amounts of muscle tissue, usually from the thigh,
removed and stored in either 90% ethanol or dimethyl sulfoxide
(DMSO). Additionally, some specimens were skeletonized in
the field, and the skeletons were soaked and stored in ethanol
before cleaning by the same procedure for skulls. A few
specimens were karyotyped in the field, as detailed below. Once
the specimens arrived at FMNH, the tissue samples were stored in
the vapor from liquid nitrogen. Older specimens were skinned
and stuffed as standard museum study skins in the field, and the
skulls were removed and cleaned. Pre-1970 specimens at FMNH
had their skulls cleaned by maceration, which sometimes caused
teeth to loosen, fall out, or both and cranial sutures to loosen,
come apart, or both.
With one exception, uncoated skulls were imaged with an
AMRAY 1810 scanning electron microscope (SEM). The
specimens were not coated with gold. Because the size of the
skulls and mandibles exceeded the photographic frame, SEM
photographs were taken of the front, middle, and back of the
skull in each view and digitally matched and merged to make
the images presented here. The skull of the holotype of A.
sacobianus was photographed with a digital camera.
Our investigations used qualitative aspects of the external,
cranial, and dental morphology; quantitative assessment of
mensural craniodental similarities and differences by principal
components analysis (PCA); and genetic data. We conducted
these studies simultaneously, with the results of each causing
us to re-examine and extend our examination of the others. In
this paper, we take the results of quantitative morphometric
studies as our starting point then present the results from our
genetic studies that provide a phylogenetic context generally
lacking from the quantitative morphological studies. We also
present information on the karyology of four of the species.
We follow this with detailed descriptions and comparisons of
anatomy for each species, emphasizing the distinctive features
that are not captured by measurements. Within the individual
species accounts, we also include additional quantitative
assessments of craniodental morphometric variation within
individual species and among sets of closely related species,
and often include bivariate plots to document differences
among them and as an aid to identification for future studies.
All specimens collected since 2000 have been prepared and
cataloged at FMNH, as described above. Upon completion of
this study, approximately half of the specimens will be
permanently deposited at the NMP, including all of the
holotypes of the species named here. All of the authors of
this publication are intended as authors of all species names
proposed herein.
Specimens collected before about 1970 often had localities
with elevation recorded in feet. Inspection of the elevations
indicates that these were estimates, often rounded to the
nearest 500 or 1000 feet. We retain these original data in the
following text but also provide the elevation converted to
meters, rounded to the nearest 100 m for the convenience of
the reader.
Measurements and Morphometric Analyses
Measurements of total length (TL), length of tail vertebrae
(TV), length of hind foot including claws (HF), length of ear
from notch (EAR), and weight in grams (WT) were taken
from our field catalogs housed at FMNH or from the tags on
older specimens. Our field measurements were taken with
plastic rulers graduated to 1 mm or with Pesola scales
graduated to 1 g. The length of head and body (HBL) was
determined by subtracting length of tail from total length.
Eighteen cranial and dental measurements were taken from
individuals, with sample sizes listed in the tables. For our
sample, we chose adults that had complete skulls. Adults were
defined as those individuals with adult pelage (not the grayer
pelage of young animals), cranial sutures (especially the
basicranial sutures) fused or nearly so, and molar teeth
showing at least moderate wear. Most adult females had
enlarged nipples, and most males had testes of relatively large
size. Heaney took all cranial measurements with dial calipers
graduated to 0.01 mm. The following measurements were
taken: basioccipital length (BOL; from anterior edge of
premaxillary to posterior edge of occipital condyles); least
interorbital breadth (IB); greatest zygomatic breadth (ZB);
mastoid breadth (MB); nasal length (NL); length of incisive
foramen (LIF); rostral depth (RD; taken from the midpoint of
the premaxillary–maxillary suture to the nearest point on the
dorsum of the rostrum); rostral length (RL; taken from
anteriormost point of orbit to the tip of the nasals);
orbitotemporal length (OL; taken from the anteriormost point
of the orbit to the posteriormost point of the temporal fossa);
alveolar length of maxillary molariform teeth (M1–M3); labial
palatal breadth at the first upper molar (PBM1); diastema
length (DL); postpalatal length (PPL; from the posterior edge
of palate to anterior edge of foramen magnum); lingual palatal
breadth at the upper third molar (LBM3); braincase height
(BH; taken at the midline); breadth of M1 (BM1); breadth of
upper incisors (BIT; near tip but below the wear surface); and
width of the zygomatic plate (ZP; at its midpoint).
We used Microsoft Excel for Windows (version 2007) to
calculate descriptive statistics (mean, standard deviation, and
observed range) for sample groups. We assessed quantitative
phenetic variation in craniodental morphology through PCA
with the use of the correlation matrix of log-transformed
measurements of adult specimens using SYSTAT 10 for
Windows (SPSS Inc., 2000). Samples included adults of both
sexes, usually 10–12 individuals per sex per locality or species,
as shown in the tables. Samples were smaller only when more
adult individuals were not available. We conducted analyses
that included several combinations of taxa, such as all species,
sets of closely related species, and geographic populations
within species, as described below. We considered any
component with an eigenvalue of less than 1.5 to be not
meaningfully interpretable and have dealt cautiously with
eigenvalues between 2.0 and 1.5, as indicated in the text.
DNA Sequencing and Phylogenetic Analyses
We extracted DNA from and sequenced the entire
cytochrome (cyt) b gene for 107 individuals of Apomys.
Sequences have been submitted to GenBank under accession
numbers HM370984–HM371090; accession numbers for all
analyzed individuals are listed in Appendix 1. The alignment
and trees have been deposited with TreeBASE accession
S10997. Our use of informal species designations for
undescribed species in the small-bodied group (e.g., ‘‘sp. F’’)
follows Heaney et al. (1998) and Steppan et al. (2003), except
that their ‘‘sp. D’’ has been described as A. camiguinensis by
Heaney and Tabaranza (2006).
We extracted total genomic DNA from liver or muscle
tissue stored in ethanol according to standard phenol/
chloroform extraction techniques. We amplified the entire
cyt b gene by polymerase chain reaction (PCR) following
procedures described in Steppan et al. (2003). All PCR
reactions included a negative control (no template DNA),
intended to identify any instances of contamination of
reagents, and were visualized on agarose gels with ethidium
bromide. Successful reactions were prepared directly by
enzymatic digestion with Exo-SAP-IT (USB Corp., USA).
Both strands of each PCR product were completely sequenced
with PCR and internal primers. Products were sequenced by
automated DNA sequencing on an ABI 3100 with the use of
big-dye terminator chemistry (Applied Biosystems, USA).
Sequences were aligned by Sequencher 4.1 (Genecodes).
To verify the taxonomy of individuals attributed to A. datae
and A. abrae, we also sequenced individuals collected from the
type localities. For specimens from the 1940s and 1950s, we
conducted extractions on bits of dried tissue left adhering to
museum skulls (FMNH 62709, 62724, 62749, 92759, 92760), the
sequencing products of which are referred to as ‘‘ancient
DNA.’’ Standard procedures were modified by the addition of
10 ml N-phenacylthiazolium bromide (PTB) solution to the
200 ml of extraction buffer to break DNA–protein crosslinking (Poinar et al., 2003), incubating for 36 hours rather
than overnight. All extractions were conducted in an isolated
5
lab free of PCR products, and ancient DNA PCR and cloning
were conducted in a lab that had never worked on mammalian
DNA. We amplified a portion of cyt b in two overlapping
fragments of approximately 110 base pairs in length each, with
the use of primer pairs S205/S206 (CCCCCTCCAAYATTTCATCCTGATGAAA/GTKACTGAGGAGAAGGCAGT)
and S207/S208 (TCTAGCCATACACTATACATCAG/
CGTCCTACGTGTAGAAATAAGCAG), modified from
primers L14841/H14927 and L14925/H15052, respectively,
from Kuch et al. (2002), tailored to match Apomys. PCR
products were then cloned with the TOPO TA cloning kit
from Invitrogen and vector pCR 2.1-TOPO (3.9 kb). The
recombinant plasmids were isolated with Qiaprep spin
columns from Qiagen. Presence of insert and the size of the
insert were verified by EcoR1 restriction digest and gel
electrophoresis. Three to five clones of each ancient sample
were sequenced using the vector primers m13r and m13f.
Phylogenetic analyses were conducted using maximumlikelihood (ML) and Bayesian approaches as implemented in
PAUP* 4.0b10 (Swofford, 2002) and MrBayes ver. 3.1.2
(Huelsenbeck & Ronquist, 2003). Support values are reported
below for ML analyses as bootstrap values (bp) and for Baysian
analyses as posterior probabilities (pp). The analytical model
(GTR with invariant sites and gamma distributed rates) was
identified using Akaike’s Information Criterion as implemented
in Modeltest 3.04 (Posada & Crandall, 1998) on one of the
maximum parsimony (MP) trees. We then conducted a ML
search using the preferred model with parameters fixed at the
values estimated on the MP tree. A heuristic search was
conducted with ten random-addition replicates and TBR
branch swapping. Bayesian analysis was run with two heated
chains and default settings for 10 million generations each. The
data were partitioned by codon, and all parameter values were
estimated for each partition separately (unlinked). Convergence
was estimated by means of diagnostics from AWTY (Wilgenbusch et al., 2004) as well as by examination of likelihood plots
and posterior probabilities of individual clades for subsets of
the runs. Trees were recorded every 2000 generations and the
first 20% were discarded as burn-in. Nonparametric ML
bootstrapping (Felsenstein, 1985) was performed with 200
replicates, each consisting of five random-sequence addition
replicates, each of which was limited to 2000 rearrangements.
Karyology
Karyotype preparations were made in the field from freshly
caught specimens of some taxa. For live-trapped animals,
bone marrow cells were processed with the use of in vivo
methods (Patton, 1967, as modified by Rickart et al., 1989).
For specimens captured in snap traps and recovered shortly
after death, cells were processed with a modified in vitro
technique (Rickart et al., 1998). Fixed cell preparations were
stored at 270uC within one month of field processing, and
standard karyotypes (undifferentially stained with giemsa)
were prepared after several months of storage. A minimum of
10 chromosome spreads was examined from each preparation.
Chromosome terminology follows Rickart and Musser (1993).
As used here, fundamental number (FN) refers to the total
number of chromosome arms (including those of sex
chromosomes) in the female karyotype. Because of variation
in preparation quality and the presence of very tiny secondary
arms on some chromosomes, we use the symbol ‘‘$’’ to
indicate what we consider to be minimum FN values.
6
Results
The Definition of Apomys
Apomys is defined as including the most recent common
ancestor of A. datae, A. gracilirostris, A. hylocoetes, A.
musculus, and all its descendants. They are medium to small
mice, with adults weighing from as little as 18 g (Apomys
musculus; Heaney et al., 1999) to as much as 128 g. The general
appearance (Figs. 1, 2) resembles individuals of Peromyscus,
Apodemus, Praomys, and many other muroid genera. The tail
is nearly equal in length to, or longer than, the head and body
and usually is dark dorsally and pale to white ventrally,
usually with a sharp boundary. The eyes and ears are large.
The fur is soft and thick, darker dorsally than ventrally; the
ventral fur is paler, often nearly white with an ochraceous
wash. The hind feet are moderately long and narrow, have six
plantar pads, and have digits 2–4 notably longer than digit 5
and the hallux. All species have two pairs of inguinal
mammae.
The skull (Fig. 4) is similar in general appearance to those
of many murids of similar size, but a combination of eight
characters uniquely diagnoses the genus (Musser, 1982;
Musser & Heaney, 1992). 1) The rostrum is moderately to
distinctly long and narrow. The premaxillaries project well
beyond the anterior edges of the incisors; together, with the
equally elongate nasals, this forms a somewhat tubular
structure. 2) The incisive foramina are rather broad,
especially relative to their length. 3) The bony palate is wide
and long, ending posterior to the last molar, with a ridge
along the posterior margin. It is textured by many tiny pits
and perforations, particularly on the posterior half to onethird of its length. 4) Each upper third molar is small and
peg-like, but with a small cusp at the anterolabial margin
(absent on worn teeth). 5) The occlusal surface of each first
and second upper molar consists of three chevron-shaped
laminae on which cusps are barely evident or absent. 6) The
occlusal surface of each first lower molar consists of a large,
inverted, heart-shaped structure at the front that forms
about half of the tooth, followed by a chevron-shaped
lamina and a small posterior cingulum. 7) Each auditory
bulla is separated from the squamosal and alisphenoid by a
gap of variable size; the gap represents the coalesced
postglenoid foramen, the postalar fissure, and the middle
lacerate foramen. 8) Most species have a subsquamosal
fenestra (5 squamoso-mastoid fenestra) that is evident as a
notch dorsal to the auditory bulla. Additionally, we note that
adult male Apomys have the posterior tip of the scrotum
(roughly 10% of the scrotum) covered with a densely
pigmented, dark spot. A similar pigmented area occurs in
Chrotomys and Rhynchomys.
Apomys is the basal member of a clade that also includes
Archboldomys, Chrotomys, and Rhynchomys (Jansa et al.,
2006; Heaney et al., 2009). Although no gene sequence data
are available from some Indo-Australian genera of interest,
this Philippine clade is well supported by multiple nuclear and
mitochondrial genes as most closely related to the remaining
members of the Hydromyini sensu Rowe et al. (2008), all of
which are confined to New Guinea, Australia, and adjacent
islands (Rowe et al., 2008). Chiropodomys, a genus confined to
continental SE Asia, the Sunda Shelf, and Palawan, is the
sister-group to the Hydromyini sensu Rowe et al. (2008; see
also Heaney et al., 2009).
FIG. 4. Crania and mandibles of Apomys (Megapomys) datae (A, C, E, F; FMNH 188445) and Apomys (Apomys) hylocoetes (B, D, G, H; FMNH
148146), dorsal (A, B), ventral (C, D), lateral (E–H); scale bar 5 5 mm.
Carotid Circulatory Patterns
As noted by Musser (1982), the basicranial arterial
circulatory patterns in A. abrae and A. datae have discrete
and fundamental differences; we follow him in referring to
these as the ‘‘abrae pattern’’ (Fig. 5A) and ‘‘datae pattern’’
(Fig. 5B). In A. datae (Fig. 5B), the carotid artery produces a
branch, the stapedial artery, near the posterior margin of the
bulla. The carotid artery continues anteriorly through the
carotid canal into the cranial cavity where it passes beneath
the brain. The stapedial artery enters the bulla through a canal
that leads to the stapedial foramen, which lies between the
bullar capsule and the petrosal portion of the petromastoid
bone. This stapedial foramen is visible on the bulla of a clean
skull under low magnification and is visible to the naked eye of
many people. The artery proceeds through the bulla and
emerges in the middle lacerate foramen as the internal
maxillary artery, which courses through a groove in the
pterygoid plate and through the foramen ovale into the
alisphenoid canal and sphenoidal fissure and eventually into
the orbit. This configuration of the carotid circulatory pattern
is widespread in murids, and it is present in Archboldomys,
Chrotomys, and Rhynchomys, which form the sister-group to
Apomys (Balete et al., 2006, 2007; Jansa et al., 2006); we
7
TABLE 1. Character loadings, eigenvalues, and percent variance
explained on the first four components of a principal components
analysis of log-transformed measurements of adult large-bodied
Apomys (see Fig. 6 and Methods).
Principal component
Variable
FIG. 5. Diagrammatic drawing of the basicranial region of Apomys
in ventral view, showing the two types of carotid circulatory patterns.
(A) The ‘‘abrae type’’; (B) the ‘‘datae type.’’ Redrawn from Musser,
1982. Abbreviations: ab, auditory bulla; al, alisphenoid bone; cc,
carotid canal; ic, internal carotid artery; im, internal maxillary artery;
sq, squamosal bone; sta, stapedial artery; stf, stapedial foramen.
1
Basioccipital length
0.924
Zygomatic breadth
0.843
Rostral depth
0.839
0.789
Labial palatal breadth at M1
Mastoid breadth
0.766
Orbitotemporal length
0.762
Maxillary toothrow length
0.715
Lingual palatal breadth at M3 0.711
Nasal length
0.690
Interorbital breadth
0.650
Diastema length
0.644
Postpalatal length
0.625
Breadth of incisors at tip
0.621
Width of zygomatic plate
0.618
Rostral length
0.600
Incisive foramen length
0.541
0.488
Breadth of M1
Braincase height
0.479
Eigenvalue
8.665
Percent variance explained
48.14
2
3
4
0.131
0.125
20.028
20.485
0.211
20.300
20.525
20.319
0.405
0.082
0.320
0.272
0.105
20.184
0.616
20.306
20.401
0.374
1.947
10.82
20.210
0.147
20.094
0.070
0.232
20.120
0.037
20.237
0.109
0.276
20.462
20.394
0.123
0.049
0.059
20.372
0.584
0.448
1.363
7.57
0.023
20.097
20.221
0.122
0.002
20.216
20.075
0.072
0.275
0.285
0.216
20.320
20.507
0.279
0.270
0.133
0.112
20.302
0.965
5.36
Quantitative Morphometric Variation within Large-Bodied Apomys
presume it to be the primitive condition in Apomys. It is
present in A. datae, A. aurorae sp. nov., A. gracilirostris, A.
magnus sp. nov., A. minganensis sp. nov., and A. zambalensis
sp. nov., as detailed below.
In A. abrae (Fig. 5A), the carotid artery produces a
stapedial artery that enters the bulla through a foramen that
is too small to be seen with the naked eye and is seen only with
difficulty under low magnification. This artery ends within the
otic region of the bulla. The carotid artery proceeds anteriorly
through the carotid canal into the cranial cavity; at the point
of entering the cranial cavity, it produces the internal
maxillary artery. The internal maxillary proceeds through a
conspicuous groove in the alisphenoid wing of the pterygoid
plate, thence through the sphenoidal fissure into the orbit.
This condition is present in A. abrae, A. banahao sp. nov., A.
brownorum sp. nov., A. sacobianus, and A. sierrae sp. nov.; we
have noted no variation within any of these species. Because
this condition is unusual within murids and absent in the
sister-clade to Apomys, we consider it to be derived within
Apomys.
On the basis of our assessment of polarity, the molecular
phylogeny presented below implies that the primitive ‘‘datae
pattern’’ is retained in A. gracilirostris (the basal species in the
clade), A. datae, and the clade that includes A. minganensis sp.
nov., A. magnus sp. nov., A. aurorae sp. nov., and A.
zambalensis sp. nov. The derived condition (the ‘‘abrae
pattern’’) developed independently three times: in A. brownorum sp. nov. and A. banahao sp. nov., in A. abrae, and in A.
sierrae sp. nov. Because the phylogenetic position of A.
sacobianus is unknown, we do not know whether its possession
of the derived condition is shared with one of the other species
or is also derived independently. The basicranial arterial
patterns are highly useful as diagnostic features of species in
Apomys, but apparently they are not consistent indicators of
phylogenetic relationships as inferred from cyt b sequence data
analysis.
8
We conducted a PCA of 18 craniodental measurements of
individuals representing all of the genetic units identified
below on the basis of data summarized in the tables of
measurements that appear below. Because the genetic data
showed that animals from high elevations are often distinct
from those at low elevations in a given area, we measured
specimens along as complete a portion of the elevational
gradient as possible in every case. We included individuals
from every geographic region from which we have specimens
with complete skulls, to determine whether the operational
units apparent in the craniodental morphometric data are
evident as monophyletic groups in the genetic data also. In this
analysis, we excluded the Mindoro species A. gracilirostris.
Compared with the other species, it is morphologically
divergent, possessing an elongate rostrum, globose braincase,
and narrow incisors, conformations not seen in any of the
Luzon species. Including this distinctive species with the
others, which resemble each other more closely, would have
dominated the pattern of variation and obscured fine
discrimination among the remaining taxa.
The PCA produced four axes with eigenvalues that exceed
or nearly equal 1.0 (Table 1), which explained 48.1%, 10.8%,
7.6%, and 5.4% of the variance in the data set (71.9% total).
Loadings on the first axis are all positive and fairly high,
indicating that this is an axis that primarily shows overall size.
The second axis has strong positive loadings for nasal, rostral,
and diastema length and braincase height, and strong negative
loadings for the length of the maxillary toothrow, labial
breadth of the palate at M1, lingual palatal breadth at M3, and
breadth of M1. This axis thus contrasts individuals with long
rostra, nasal bones, and diastema, high braincase, short molar
toothrows, narrow palates, and narrow M1, with individuals
having the converse.
The third axis (Table 1), with a marginally interpretable
eigenvalue of 1.4, had high positive loadings for breadth of M1
FIG. 6. Results of the principal components analysis of all taxa;
see Table 1 and text for details. (A) Principal component (PC) 2 vs.
PC 1; (B) PC 4 vs. PC 3.
and braincase height and high negative loadings for diastema
length, length of the incisive foramina, and postpalatal length.
This axis contrasts individuals with wide M1; high braincases;
and short diastemas, incisive foramina, and postpalatal
regions with those that have the converse.
The fourth axis is not interpretable, with an eigenvalue of
0.965. It primarily contrasts individuals with upper incisors
that are narrow at the tip with those that are wider at the tip.
A plot of the first two axes (Fig. 6A) shows overlap among
many named species and previously unnamed, geographically
defined populations, but clear patterns and differences are
nevertheless evident. Specimens from the lowlands of Mt.
Banahaw (A. magnus sp. nov.) scored highest on the first axis,
and specimens of A. abrae and those from the high elevations
on the Zambales Mountains (A. brownorum sp. nov.) scored
lowest, reflecting their status as the largest and smallest of
these species. Other species fell toward the middle of the range
and overlapped extensively. Apomys datae scored highest on
the second axis, reflecting its long rostral region (including the
diastema), high braincase, narrow M1, and narrow palate
(and, we note from examination of skulls, the palate is also
short). Most individuals from the Sierra Madre (A. sierrae sp.
nov.) scored low on this axis, reflecting their shorter rostrum,
low braincase, and wide M1.
Close inspection of Figure 6A shows additional patterns.
Apomys abrae and A. datae, which co-occur in the Central
Cordillera, show limited overlap on these two axes. Specimens
from high (A. brownorum sp. nov.) and low (A. zambalensis sp.
nov.) in the Zambales Mountains show no overlap; the same is
true for specimens from high (A. banahao sp. nov.) and low (A.
magnus sp. nov.) on Mt. Banahaw, and from high (A.
minganensis sp. nov.) and low (A. aurorae sp. nov.) in the
Mingan Mountains. Those from high in the Zambales (A.
brownorum sp. nov.) and on Mt. Banahaw (A. banahao sp.
nov.) do not overlap, nor do those from low in Zambales (A.
zambalensis sp. nov.) and on Mt. Banahaw (A. magnus sp.
nov.). This suggests that each of these is a distinct
morphotype, compared with a sympatric or parapatric
morphotype. But this analysis also leaves ambiguity among
some geographic populations. Individuals from the Sierra
Madre and Caraballos Mountains (described below as A.
sierrae sp. nov.) vary widely, and overlap broadly with
individuals from the Mingan lowlands and Zambales lowlands. Apomys datae overlaps fairly extensively with individuals from the high elevations on Mt. Banahaw (A. banahao sp.
nov.) and the Zambales lowlands (A. zambalensis sp. nov.),
and there is some overlap between A. datae and individuals
from the Sierra Madre and Caraballos Mountains (A. sierrae
sp. nov.).
Figure 6B, which is marginally interpretable because of low
eigenvalues, plots the scores of individual specimens on axes 3
and 4 of the PCA. Apomys from the lowlands of Zambales (A.
zambalensis sp. nov.), which fall near the center in Figure 6A,
score lowest on axis 3, indicating that they have narrow M1,
low braincases, and long diastemas and incisive foramina.
Apomys datae and specimens from the highlands of Mt.
Banahaw (A. banahao sp. nov.) have the reverse. On axis 4,
specimens from the Mingan highlands (A. minganensis sp.
nov.) score high, indicating that their incisors are especially
narrow at the tip. Specimens from the highlands of Mt.
Banahaw (A. banahao sp. nov.) scored especially low on this
axis. Specimens of A. sierrae are notably variable on this axis.
These morphometric analyses provide an overview of
differences in size and shape among geographic populations
of large-bodied Apomys, and many of these differences imply
that many distinct species are present. However, clear
resolution of species requires further data, which we provide
next in the form of genetic data from the mitochondrial DNA
genome, specifically from cyt b, followed by detailed
comparisons of external and craniodental morphology. In
the descriptions of species that follow, we also present PCAs
of selected sets of species, and of populations in geographically
widespread species, as a means of further investigating
patterns of variation, similarity, and dissimilarity.
Molecular Evidence of Relationships within Apomys
Maximum likelihood analysis of the mitochondrial gene cyt
b yielded 14 trees, all of which agreed on the among-species
9
FIG. 7. Maximum likelihood phylogeny of Apomys based on the mitochondrial gene cyt b. Pictured is one of 14 most likely trees, chosen
randomly. The trees vary topologically only with respect to apparent polytomies within species and among three lineages of A. abrae and A.
datae. Support values are ML bootstrap and Bayesian posterior probabilities, respectively, expressed as percentages, for selected nodes. The long
dash symbol (—) indicates clades B and C are not sister-groups in the maximum credible tree from Bayesian analysis. The dashed grey arrow
indicates the Bayesian placement of clade C. Unless otherwise specified, all specimen numbers are FMNH. An asterisk (*) on the specimen name
indicates source for ancient DNA or degraded frozen sample. A double asterisk (**) indicates an ancient DNA specimen collected from type
locality. Outgroups are pruned for visual clarity. Clades are color-coded by morphologically defined species. Localities and regions of selected
clades are indicated on the right. Low, medium, and high refer to relative elevation ranges.
10
topology. The only differences among the ML trees occurred
within regions of near-zero branch lengths: at the base of A.
aurorae, within A. sierrae, and among three population-level
clades of A. datae and A. abrae. Our analysis of the phylogeny
showed clear structure, with most nodes significantly resolved
down to a low divergence level (Fig. 7). Two primary clades
are evident. The first of these (A. Apomys in Fig. 7) includes all
of the small species (average 18–41 g) in the genus (A.
camiguinensis, A. hylocoetes, A. insignis, A. microdon, A.
musculus, and unnamed taxa labeled ‘‘sp. A,’’ ‘‘sp. B,’’ ‘‘sp.
C,’’ and ‘‘sp. F’’; see Heaney et al., 1998; Steppan et al., 2003).
This clade occurs widely within the Philippines except for three
areas: the Palawan region, which shares many species with
Borneo and may have been connected to Asia (via Borneo) at
some point during the Pleistocene glaciations (Heaney, 1985,
1986; Sathiamurthy & Voris, 2006); the small, isolated islands
of the Babuyan and Batanes groups that lie north of Luzon;
and the Sulu Archipelago, a seemingly depauperate but poorly
known set of small islands between Mindanao and Borneo.
These species all have tails that are substantially longer than
the length of the head and body (from 120% to 140%), and all
apparently forage frequently or primarily above ground in
grass, shrubs, trees, or a combination thereof, often in
sympatry with large-bodied species in northern and central
Luzon (Heaney et al., 1989, 1998, 1999, 2006a,b; Rickart et al.,
1993, 2011; Balete et al., 2009).
The second primary clade within Apomys (A. Megapomys in
Fig. 7) includes large-bodied animals (mean weight 66–109 g)
that occur only on Luzon and Mindoro islands, represented
among previously described species by A. abrae, A. datae, A.
gracilirostris, and A. sacobianus (the last of which could not be
included in Fig. 7 because it is known only from the holotype
collected in 1956). In addition to these species, which are
treated in detail below, many monophyletic lineages are
represented by specimens that have been obtained by our
field surveys since 2000. All of these mice have tails that are
usually about equal to but sometimes shorter than or slightly
longer than the length of head and body (84–110%), and they
forage on or occasionally slightly above the surface of the
ground (Heaney et al., 2003; Duya et al., 2007, this volume;
Balete et al., 2009, this volume; Alviola et al., this volume;
Rickart et al., 2011).
Within the large-bodied Apomys, four secondary clades are
evident in the genetic data (Fig. 7). The first of these (‘‘A’’)
consists of A. gracilirostris from Mt. Halcon, Mindoro Island,
sister to all other species. This is the only large-bodied species
of Apomys currently known from an island other than Luzon,
with the exception of a population on a small, shallow-water
island (Palaui) of a species described below that occurs on the
adjacent portion of Luzon.
The second large-bodied clade (‘‘B’’) includes two monophyletic populations from high elevations on Mt. Banahaw and on
Mt. Tapulao in the Zambales Mountains (Fig. 3), described
herein as the new species A. banahao and A. brownorum,
respectively. Although the genetic distance between them is not
great (3.6% uncorrected distance), the support values are high
(ML bootstrap 89–97 bp, 1.00 Bayesian pp), and the clade
containing these two species is genetically quite distinct from
their sister-clade. These populations were easily distinguished
from each other on principal components 1 and 2 (PC1, PC2) in
the PCA described above and differ in anatomical details
described below.
The third large-bodied clade (‘‘C’’) includes two named
species, A. abrae and A. datae. The results are equivocal as to
the exact placement of this clade; ML places it as sister to
clade ‘‘B,’’ Bayesian analysis places it as sister to clade ‘‘D,’’ as
discussed below, but neither position is well supported (20%
bp, 0.63 pp, respectively). Therefore, we consider the
relationships among clades B–D to be unresolved and
effectively a polytomy, pending further data. Monophyly of
clade C is moderately well supported, with 83% bp and 100 pp.
These two species are easily distinguished by morphological
details provided below in the species descriptions. The
remarkable pattern here is the paraphyly of both species with
respect to each other. Individuals assignable morphologically
to A. datae belong to three mitochondrial lineages, one of
which (FMNH 193554, 193655, 193877) is from Mt. Amuyao
and is moderately divergent from the rest of the complex. The
other two interdigitate with two lineages assignable to A.
abrae. Specimens from the type localities of these two species
are indicated by ‘‘**’’ and are part of this polytomy. Within
clade C, cyt b data do not support the species limits that are
indicated by morphology. There are two leading alternative
explanations for this discordance. The species could have
diverged only very recently, with the tree reflecting a lack of
sorting of the mitochondrial genome. Given that the
mitochondrial genome is quickly evolving and rapidly sorting,
we believe that this hypothesis is unlikely. Alternatively,
mitochondrial introgression might obscure the true phylogeny,
as seen in chipmunks (Good et al., 2008). In contrast to the cyt
b results, preliminary phylogenies from several nuclear genes
indicate that these species might not even be close relatives (S.
J. Steppan, unpubl. data). We are currently testing these
alternatives with additional nuclear sequence data and will
present the results elsewhere. Although we consider their
current phylogenetic placement tentative pending these further
studies, on the basis of their distinctive morphology and
extensively overlapping geographic distributions, we retain A.
abrae and A. datae as distinct species.
The fourth major clade (‘‘D’’ in Fig. 7) includes five distinct
monophyletic groups from 1) lowland portions of Mt.
Banahaw (described here as A. magnus sp. nov.), 2) Mt. Natib
and lowland portions of Mt. Tapulao in the Zambales
Mountains (described here as A. zambalensis sp. nov.), 3) the
upper and 4) lower elevations in the Mingan Mountains
(described here as A. minganensis and A. aurorae spp. nov.,
respectively), and 5) individuals from the northern Sierra
Madre, the Caraballo Mountains, and the near-shore,
shallow-water island of Palaui (described here as A. sierrae
sp. nov.). Clade D is the least well supported of the major
large-bodied clades, with 62% bp and 0.99 pp.
The first species to diverge in this group is A. minganensis
sp. nov. from the highlands of the Mingan Mountains. Its
genetic distance to other groups is high (7–8% uncorrected,
11–12% ML distances), and support values are strong (100%
bp, 1.00 pp), clearly showing this as an evolutionarily distinct
species. As described below, this species overlaps syntopically
with individuals of A. aurorae sp. nov. from the lowlands of
the Mingan Mountains, a species that is more closely related
to lowland populations from Mt. Banahaw (A. magnus sp.
nov.) and the Zambales/Natib area (A. zambalensis sp. nov.).
The absence of evidence of gene flow and the ease of
morphological differentiation evident in the PCA (Fig. 6A)
mark the two clades in the Mingan Mountains as necessarily
representing different species. The clades from lowland
11
Banahaw (A. magnus sp. nov.) and lowland Zambales/Natib
(A. zambalensis sp. nov.) are genetically similar to each other
and the clade from lowland Mingan, but each of these three
allopatric clades is well supported, they have limited overlap in
the PCA (Fig. 6A), and they can be easily distinguished
anatomically from one another. We conclude that each should
be recognized as a distinct species.
The ‘‘Zambales Low’’ clade (Fig. 7) is made up of
individuals from two sampling regions: Mt. Tapulao in the
Zambales Mountains and Mt. Natib in Bataan Province. The
two populations form reciprocally monophyletic groups, but
the subtending branches are very short. The PCA results and
anatomical comparisons of specimens from these areas
(described below) show no clear evidence of differences, and
we note that these two mountains are at nearly opposite ends
of a mountain chain that runs 150 km with only a few narrow
lowland gaps (Fig. 3). We predict that individuals collected in
intervening areas will show evidence of low-level isolation by
distance, consistent with recognition of the single species that
we describe here as A. zambalensis sp. nov.
The remaining clade consists of individuals from a broad
portion of the Sierra Madre and Caraballo Mountains in
northeastern Luzon, including Cagayan, Quirino, and Nueva
Viscaya provinces and the small offshore island of Palaui.
They are separated by a long, well-supported branch (99% bp,
1.00 pp) from any other clade. However, within this clade,
little if any geographic structure is apparent: individuals from
Mt. Cetaceo in Cagayan Province, from the Mungiao
Mountains in Quirino Province, and from Mt. Palali in
Nueva Viscaya are scattered almost randomly within the
clade, and the internal branches are short. The individual from
Palaui Island (FMNH 191232) is slightly divergent from the
others, which is not surprising for a population on a small
island that has been isolated by a shallow sea-channel for
about 12,000 years, and periodically during earlier Pleistocene
interglacial periods. A PCA of these populations, presented
below, showed no evidence of structure within this set of
individuals, and we see no evidence of anatomical differences,
aside from pelage (see below), among any of these populations, including the one from Palaui Island. It is therefore our
hypothesis that all of these individuals are members of a single
species, Apomys sierrae sp. nov.
We note that two genetically distinct populations occur in
the Mingan Mountains: two in the Zambales Mountains and
two on Mt. Banahaw. In each of these cases, there is no
evidence of hybridization or intermediacy in any individual,
and indeed, none of the pairs consists of sister-species. Apomys
abrae and A. datae, on the other hand, which are sympatric
over much of the Central Cordillera, currently have ambiguous relationships discussed above and below.
Karyotypic Variation
Karyotype data are available for nine species of Apomys,
more than half of the 17 species currently known (including
the 7 described here). The level of karyotypic variation within
Apomys is extreme: only two species share a common
karyotype (A. abrae and A. datae), whereas the remaining
species have highly divergent karyotypes with diploid numbers
ranging from 30 to 48 and fundamental numbers from 50 to 88
(Rickart & Musser, 1993; Rickart & Heaney, 2002). Much of
this karyotypic diversity is encompassed among species
belonging to the small-bodied clade as defined above.
12
Among the Apomys that have been karyotyped, four belong
to the large-bodied clade (Fig. 8). Apomys datae (Fig. 8A) and
A. abrae (Fig. 8B) both have karyotypes of 2n 5 44 that are
very similar, if not identical, consisting of a majority of
telocentric elements, including a large telocentric X chromosome, and distinctive pairs of biarmed autosomes. Apomys
zambalensis sp. nov. from Mt. Natib in Bataan Province also
has a karyotype of 2n 5 44 (Fig. 8C) but differs in a number
of important respects from the datae–abrae arrangement,
including a submetacentric X chromosome. The karyotype of
A. banahao sp. nov., from the high elevations on Mt. Banahaw
in Quezon Province, has 2n 5 48 (Fig. 8D), but otherwise is
most similar to that of A. zambalensis sp. nov. Each of these
karyotypes of large-bodied Apomys is similar to a common
karyotype of 2n 5 44 seen in species belonging to the other
genera of ‘‘earthworm-mice,’’ Archboldomys, Chrotomys, and
Rhynchomys (Rickart & Musser, 1993; Rickart & Heaney,
2002; E. A. Rickart, unpubl. data).
Patterns of karyotype diversity within Apomys and related
genera suggest that the large-bodied species are more
conservative, with arrangements that resemble the presumed
ancestral karyotype, whereas members of the small-bodied
clade have more highly derived karyotypes. Clearly, diversification within Apomys has often been accompanied by major
chromosomal evolution.
The Subgenera and Species of Large-Bodied Apomys
To recognize the fundamental morphological, genetic, and
ecological dichotomy within Apomys, we recognize two
subgenera within the genus. The subgenus Apomys includes
the small-bodied species, as listed below, retaining A.
hylocoetes Mearns 1905 as the type species. For the largebodied species, we propose the new subgenus Apomys
(Megapomys).
Apomys (Megapomys) New Subgenus
TYPE SPECIES—Mus datae Meyer, 1899 (5 Apomys datae
sensu Ellerman, 1941, and others).
ETYMOLOGY—From the Greek ‘‘megas,’’ meaning large or
great; ‘‘apo,’’ from Mt. Apo, the highest mountain in the
Philippines, and meaning ‘‘grandfather’’ in local languages;
and the Greek ‘‘mys,’’ meaning mouse. The gender is
masculine.
INCLUDED SPECIES—The previously described A. abrae
(Sanborn, 1952), A. datae (Meyer, 1899), A. gracilirostris
Ruedas, 1995, and A. sacobianus Johnson, 1962, and the seven
new species described below: A. aurorae, A. banahao, A.
brownorum, A. magnus, A. minganensis, A. sierrae, and A.
zambalensis.
DIAGNOSIS—The subgenus Megapomys is defined phylogenetically as the most recent common ancestor of A.
gracilirostris, A. datae, and A. zambalensis and all of its
descendants (Fig. 7), and by the following combination of
morphological characters (contrasted with the subgenus
Apomys): size large, averaging 66–109 g (vs. 18–41 g in A.
(Apomys)); average tail length ranging from 84% to 110% of
the length of head and body (vs. 120–140%); hind foot
typically relatively broader and wider (vs. longer and
narrower; see Heaney & Tabaranza, 2006); braincase more
FIG. 8. Male karyotypes of four species of the subgenus Megapomys from Luzon. (A) Apomys datae, Mt. Amuyao, Mountain Province
(FMNH 193662). (B) Apomys abrae, Balbalasang, Kalinga Province (FMNH 169051). (C) Apomys zambalensis sp. nov., Mt. Natib, Bataan Province
(FMNH 183368). (D) Apomys banahao sp. nov., Mt. Banahaw, Quezon Province (FMNH 178468).
robust, less globose (vs. more delicate and globose; Fig. 4);
rostrum proportionately broader and heavier, except in A.
(M.) gracilirostris (vs. thinner and more gracile); upper
incisors deeper in anteroposterior axis, except in A. (M.)
gracilirostris (vs. narrower); posterior bony palate more
heavily pitted and fenestrated (vs. less pitted and fenestrated);
incisive foramina proportionately broader (vs. broad, but less
so); and zygomatic arches more robust (vs. more gracile).
Some of these characters are associated with Megapomys,
being a clade of larger, more ground-living species, compared
with the smaller and more arboreal subgenus Apomys. These
two ecomorphological lineages are clearly evident in the
mitochondrial DNA-based analysis (Fig. 7).
The genus Apomys has A. hylocoetes as its type species, and
thus the nominotypical subgenus necessarily does as well. This
subgenus contains the following recognized species: A.
camiguinensis, A. hylocoetes, A. insignis, A. littoralis, A.
microdon, and A. musculus, plus several as yet undescribed
species listed by Heaney et al. (1998) on the basis of the cyt b
phylogenies presented by Steppan et al. (2003) and in Figure 7.
These species are widespread in the Philippines, with the
exception of the Palawan and Babuyan/Batanes groups of
islands and the Sulu Archipelago. On Luzon, A. microdon and
A. musculus often occur sympatrically with members of the
subgenus Megapomys (e.g., Heaney et al., 1998; Balete et al.,
2009; Rickart et al., 2011).
Because the morphometrically distinctive populations of
Megapomys are concordant with mitochondrial clades (except
A. abrae and A. datae, as discussed) and with units defined on
the basis of qualitative external and craniodental traits (as
discussed below), we recognize each of them as a distinct
species in the following pages. In the diagnoses and
comparisons that follow, we emphasize differences that
separate species from their sister-taxa and from the geographically closest species of Megapomys.
Apomys datae (Meyer, 1899)
Mus datae Meyer, 1899: 52.
Apomys major Miller, 1910: 402. Musser 1982: 73, synonym of A.
datae.
Apomys datae. Ellerman, 1941: 225. First use of current name
combination.
HOLOTYPE—Staatliches Museum für Tierkunde, Dresden
B3100 obtained in 1892 by John Whitehead. Prepared as
stuffed skin plus skull.
TYPE LOCALITY—‘‘Monte Data, Lepanto [Province], North
Luzon, Philippines’’ (5 Mt. Data, currently in Mountain
Province; see Musser, 1982).
SPECIMENS EXAMINED (n 5 882)—LUZON ISLAND: Benguet
Prov.: Haight’s-in-the-Oaks, 7000 ft [ca. 2100 m] (USNM 151513);
Mt. Pulag National Park, 0.5 km S, 0.4 km W Mt. Babadak peak,
2480 m (FMNH 198620–198632, 198638, 198639, 198643–198653,
198662–198665, 198669–198672, 198827, 198828, 198831–198833,
198835–198840); Mt. Pulag National Park, 0.7 km S, 0.4 km W Mt.
Babadak peak, 2445 m (FMNH 198536, 198583–198604, 198611–
198615); Mt. Pulag National Park, 0.8 km S, 0.4 km W Mt. Babadak
peak, 2420 m (FMNH 198579–198582, 198640, 198641, 198654, 198673,
198811–198819, 198834); Mt. Pulag National Park, 0.8 km S, 0.9 km
13
FIG. 9. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys datae (FMNH 188445;
adult female from Mt. Data); scale bar 5 5 mm.
W Mt. Babadak peak, 2285 m (FMNH 198616, 198617, 198633–198637,
198642, 198655–198659, 198667, 198668, 198674–198676, 198825,
198826, 198830); Mt. Pulag National Park, 0.9 km S, 0.9 km W Mt.
Babadak peak, 2335 m (FMNH 198605–198610, 198618, 198619,
198660, 198661, 198666, 198677, 198820–198824, 198829); Mt. Pulag
National Park, 0.5 km S, 0.7 km E Mt. Pulag peak, 2800 m (FMNH
198539–198543, 198549, 198798, 198801); Mt. Pulag National Park,
0.6 km S, 0.65 km E Mt. Pulag peak, 2730 m (FMNH 198550–198555,
198565–198568, 198570, 198571, 198804–198807); Mt. Pulag National
Park, 1.15 km S, 1.35 km E Mt. Pulag peak, 2695 m (FMNH 198556–
198564, 198572–198578, 198802, 198803, 198808–198810, 202538);
Mt. Pulag National Park, 1.2 km S, 1.15 km E Mt. Pulag peak, 2780 m
(FMNH 198544, 198545, 198548, 198799, 198800); Mt. Pulag National
Park, 1.35 km S, 0.8 km E Mt. Pulag peak, 2740 m (FMNH 198537,
198538, 198546, 198547, 198569); Mt. Pulag National Park, 1.75 km
S, 0.9 km E Mt. Pulag peak, 2650 m (FMNH 198678–198707, 198841–
198852).
Ifugao Prov.: Kiangan Munic.: Brgy. Duwit (5Brgy. Duit), 4000 ft
[ca. 1200 m] (USNM 557717). Ilocos Norte Prov.: Tagudin (AMNH
252474–252475).
Kalinga Prov.: Balbalan Munic.: Balbalasang Brgy.: Am-licao,
1800 m (FMNH 169071–169121, 170931–170964, 170982); Balbalan
Munic.: Balbalasang Brgy.: Magdallao, 1600 m (FMNH 167243,
167244, 167246–167253, 167255–167257, 167260, 167263–167272,
167278–167284, 167288–167291, 167293, 167295–167298, 167302,
167329–167341, 167345, 167348, 167350–167354, 167357, 167359,
167360, 167362–167366); Balbalasang Brgy.: Mt. Bali-it, 1950 m
(FMNH 175415–175498, 175630–175681, 175732); Balbalan Munic.:
Balbalasang Brgy.: Mt. Bali-it, 2150 m (FMNH 175499–175546,
175682–175717, 175733).
Mountain Prov. (no specific locality; FMNH 62761, 62762); 0.6 km N
Barlig Munic. Hall, 1800 m (FMNH 193548, 193549, 193877); 0.4 km
N, 0.4 km W Mt. Amuyao peak, 2480 m (FMNH 193599–193614,
193884–193886); 0.5 km N, 0.5 km W Mt. Amuyao peak, 2530 m
(FMNH 193550–193559, 193878–193883); 0.75 km W Mt. Amuyao
peak, 2300 m (FMNH 193615–193636, 193910–193919); 1.0 km N,
1.0 km W Mt. Amuyao peak, 2150 m (FMNH 193637–193659, 193920–
193931); 1.25 km N, 0.5 km W Mt. Amuyao peak, 1990 m (FMNH
14
193660–193662); 1.75 km N, 0.4 km W Mt. Amuyao peak, 1885 m
(FMNH 193932–193940, 193663–193675); 1.75 km N, 1.5 km W Mt.
Amuyao peak, 1950 m (FMNH 193676–193680); Mt. Amuyao peak,
2690 m (FMNH 193560–193598, 193887–193909); Mt. Data (FMNH
62697, 62698, 62701–62705, 62707, 62708, 62710, 62713–62718,
62721, 62722, 62729, 62730, 62732, 62735–62737, 62742, 62745–
62747); Mt. Data, 5300 ft [ca. 1600 m] (FMNH 62731); Mt. Data, 7500 ft
[ca. 2300 m] (FMNH 62695–62696, 62699, 62720, 62725); Mt. Data,
8000 ft [ca. 2400 m] (FMNH 62727, 62733–62734, 62741, 62744); Mt.
Data, 8200 ft [ca. 2500 m] (FMNH 62706, 62709, 62711); Mt. Data,
8300 ft [ca. 2500 m] (FMNH 62712); Mt. Data, Cotcot (FMNH 62743,
62748); 0.1 km E south peak Mt. Data, 2310 m (FMNH 188298–
188306, 188310–188312, 188438–188445); 0.75 km N, 0.6 km E south
peak Mt. Data, 2241 m (FMNH 188245–188277, 188425–188427,
188429–188436, 188493); 0.75 km N, 0.75 km E south peak Mt. Data,
2289 m (FMNH 188287–188291, 188448); 0.75 km N, 1.0 km E south
peak Mt. Data, 2289 m (FMNH 188278–188286, 188307–188309,
188446, 188447).
EMENDED DIAGNOSIS AND DESCRIPTION—A large mouse
(HBL averaging 137–144 mm, BOL averaging 34–36 mm in
populations summarized in Table 2), with a tail that averages
shorter than the length of head and body (89–95%; Table 2;
Figs. 1B, 9). The fur is dense, soft, and dark brown with a
slight rusty-orange tint dorsally. The ventral fur is either white
at the tips, or with a pale ochraceous wash, and dark gray at
the base. The fur on the dorsal surface of the forepaws and
hind feet is white on the distal half, with dark fur extending
over approximately the basal half. The tail is darker dorsally
than ventrally, often with a sharp line demarcating the upper
and lower halves, but some scattered black hairs are often
present on the ventral surface of the tail. The skin of the lips
and lower rhinarium is darkly pigmented, as is the inside
surface of the base of the pinna. The hind feet are of moderate
length, with fairly large and well-separated pads, and usually
are darkly pigmented over the proximal half to two-thirds of the
ventral surface. The plantar pads are large, and the toes are
slightly short and stocky (Fig. 10B). The cranium is relatively
large and robust, with a deep, squarish braincase and a long,
stout rostrum that is associated with a long diastema. The
interparietal bone is of variable shape, but usually moderately
wide (anteroposteriorly) and roughly oval in shape. The
maxillary toothrow is moderately short, the palate is narrow,
and the toothrows diverge slightly posteriorly (Fig. 9B;
Table 2). The postpalatal region is of moderate length. The
stapedial artery enters each bulla through a distinct foramen
between the bullar capsule and the petrosal portion of the
petromastoid bone (the ‘‘datae pattern’’; Fig. 5B). The mandible is robust and deep. The coronoid process is slender, sharply
pointed, and moderately long; the angular process is sturdy,
with the posterior margin of the mandible sweeping down in a
shallow arc from the condylar process (Fig. 9C).
On the basis of two males from Mt. Amuyao, Mountain
Province (FMNH 193558, 193662), and one from Mt. Bali-it,
Kalinga Province (FMNH 169111), the karyotype of A. datae
has 2n 5 44 and FN $ 54 (Fig. 8A). The available
preparations are of marginal quality, but the karyotype
appears to be very similar to that of A. abrae (described
below in greater detail).
To assess geographic variation, we conducted a PCA of 18
craniodental measurements in Table 2 from the four populations of A. datae from which we have adequate samples: Mt.
Pulag (Benguet Province), Mt. Data and Mt. Amuyao
(Mountain Province), and Mt. Bali-it and vicinity (Kalinga
Province); these represent populations from the southern,
central, and northern portions of the species’ range. The first
principal component (PC1), which accounted for 36% of the
variation, had moderate to high positive loadings for all
variables, with the exception of length of incisive foramen,
which has a loading barely above zero (Table 4); this
component appears to represent overall size. The second
component (PC2), which accounted for 11% of the variation,
had high positive loadings on length of incisive foramen and
diastema and labial breadth at M3 and high negative loadings
on length of the molar toothrow, braincase height, and
breadth of M1. The next two components had eigenvalues of
1.2 or less. Individuals from all four areas overlapped
extensively on the first two PCs, with no evident geographic
pattern (Fig. 11). Given this lack of quantitative craniodental
differences, and the consistent qualitative cranial and external
morphology, we regard all of the specimens included in
Specimens Examined as being examples of a single species.
COMPARISONS—Relative to most other Megapomys, the
cranium of A. datae is large and robust, with a deep, squarish
braincase, a long, stout rostrum, and a long diastema. As
detailed below, relative to some other species, the maxillary
toothrow is short, the palate is narrow, and the postpalatal
region is of moderate length (Fig. 9; Table 2). In A. datae, the
stapedial artery enters each bulla through a distinct foramen
between the bullar capsule and the petrosal portion of the
petromastoid bone (the ‘‘datae pattern’’; Fig. 5B), as discussed
above under Carotid Circulatory Patterns.
Compared with A. abrae, the tail is short relative to the
length of head and body, averaging 89–95% (97–101% of HBL
in A. abrae; Table 2). A plot of weight and relative length of
the tail (Fig. 12A) shows overlap, but most individuals are
outside of the area of overlap. The dorsal pelage of A. abrae
(Fig. 1C) typically is a rich, dark brown, whereas that of A.
datae is equally dark, but has a rusty, slightly orange tinge
(Fig. 1B); although, as noted below, some specimens of A.
abrae are much paler. Apomys abrae rarely have any black
hairs on the ventral surface of the tail, whereas scattered black
hairs are often present on A. datae, and the scales are usually
pale gray, not white as in A. abrae. The fur on the dorsal
surface of the forepaws and hind feet of A. abrae is white or
with very few scattered dark hairs (vs. having dark hairs
extending over much of the tops of the feet). The hind feet of
A. abrae (Fig. 10A) are paler, slightly shorter on average, and
proportionately narrower, than those of A. datae (Table 2).
Additionally, the toes are slightly longer, and the plantar pads
are smaller and more widely separated than those of A. datae
(Fig. 10B).
The cranium of A. datae is larger than that of A. abrae in
nearly every dimension, with little overlap in zygomatic
breadth, mastoid breadth, nasal length, rostral depth, rostral
length, width of the zygomatic plate, and postpalatal length
(Table 2). For example, plots of zygomatic breadth and
mastoid breadth (Fig. 12B) and rostral length and rostral
depth (Fig. 12C) show very little overlap, and serve to easily
distinguish most individuals. The interparietal bone is variable
in both species but is usually anteroposteriorly wider in A.
datae than in A. abrae. Relative to A. datae, the mandible of A.
abrae is shorter and less deep, with a shorter coronoid process,
less robust angular process, and more concave posterior
margin between the condylar and coronoid processes.
A PCA of individuals that we refer to A. datae and A. abrae
using 18 craniodental measurements (Tables 2, 3) showed
significant and interpretable variation on two components
(Fig. 13; Table 5). The first component loaded heavily on
nearly all measurements (Table 5) and accounted for 51% of
the total variation; only length of incisive foramen had a low
loading. This axis was thus an overall measure of size and
robustness. The second component loaded heavily and
positively on length of incisive foramen and diastema length
and negatively on length of the molar toothrow, palatal
breadth at M1, and breadth of M1. A plot of these two
components (Fig. 13) showed that specimens with qualitative
features associated with A. abrae scored low on PC1, and A.
datae scored high; this is consistent with our observation
regarding relative size and robustness of these two species,
with some overlap that we suspect is associated with agerelated variation in size. PC2 had great overlap, such that it
does not assist in distinguishing between these species. Taking
all of the available data together, it appears that the
differences in carotid artery circulatory patterns, pelage
coloration, and overall size are the best means to distinguish
between these two species.
DISTRIBUTION—Apomys datae occurs widely in the high
mountains of the Central Cordillera of northern Luzon Island.
Verified records are from Benguet, Ifugao, Kalinga, and
Mountain provinces, from 1500 to 2800 m in elevation
(Figs. 3, 14). This species overlaps broadly with A. abrae,
but A. datae usually occurs in more mature forests, in moister
habitats, and at higher elevations, although they occur
syntopically in some places (Rickart et al., 2011; Fig. 15).
Surveys are needed to determine the distribution of this species
in the northernmost Central Cordillera, in Abra, Apayao, and
Ilocos Norte provinces, and in the southeastern Central
Cordillera where this range abuts with the Caraballo
Mountains, which support A. sierrae sp. nov.
15
TABLE 2. Cranial and external measurements (mean 6 1 S.D. and range) of Apomys datae and A. abrae (part).
Apomys datae
Mt. Data, Mountain Prov.
Measurement
Basioccipital
length
Interorbital
breadth
Zygomatic
breadth
Mastoid breadth
Nasal length
Incisive foramen
length
Rostral depth
Rostral length
Orbitotemporal
length
Labial palatal
breadth at M1
Diastema length
Postpalatal length
Lingual palatal
breadth at M3
Braincase height
Breadth of M1
Breadth of
incisors at tip
Width of
zygomatic plate
Length of head
and body
Total length
Length of tail
vertebrae
Length of hind
foot
Length of ear
Weight (g)
M (n = 10)
F (n = 10)
35.51 6 0.75
34.14–36.77
6.14 6 0.28
5.60–6.50
18.55 6 0.40
17.85–18.99
14.68 6 0.36
14.23–15.48
15.15 6 0.50
14.14–15.85
4.94 6 0.27
4.58–5.29
7.73 6 0.30
7.14–8.21
16.43 6 0.50
15.51–17.02
11.64 6 0.27
11.21–11.98
7.06 6 0.23
6.82–7.53
7.31 6 0.21
7.07–7.70
9.45 6 0.33
9.11–10.06
12.11 6 0.32
11.72–12.61
5.03 6 0.23
4.57–5.38
11.42 6 0.32
11.00–11.96
1.87 6 0.05
1.81–1.95
2.32 6 0.11
2.13–2.48
3.55 6 0.17
3.20–3.74
144.7 6 6.9
130–154
279.5 6 7.6
260–287
134.8 6 4.6
126–141
37.3 6 0.9
36–38
21.0 6 0.7
20–22
91.6 6 7.0
78–102
34.82 6 0.62
34.06–35.90
6.07 6 0.36
5.29–6.50
18.60 6 0.27
18.09–19.15
14.53 6 0.35
13.86–14.94
14.61 6 0.54
13.89–15.42
4.77 6 0.20
4.48–5.13
7.70 6 0.22
7.43–8.02
16.15 6 0.40
15.71–17.09
11.68 6 0.39
11.28–12.60
7.09 6 0.16
6.89–7.34
7.37 6 0.14
7.22–7.70
9.22 6 0.25
8.89–9.71
11.89 6 0.38
11.28–12.36
5.08 6 0.28
4.59–5.47
11.45 6 0.34
10.58–11.81
1.90 6 0.06
1.84–2.03
2.24 6 0.09
2.08–2.37
3.43 6 0.22
3.12–3.78
141.0 6 6.0 (9)
129–149
273.3 6 8.0 (9)
257–286
132.1 6 3.6
128–139
36.2 6 1.5
33–38
20.3 6 0.9
18–21
81.8 6 9.8 (9)
70–97
Balbalasang, 1900–2150 m,
Kalinga Prov.
M (n = 10)
34.75 6 0.72
33.65–35.82
5.79 6 0.35
5.20–6.58
18.34 6 0.41 (9)
17.90–18.98
14.08 6 0.30
13.53–14.49
14.07 6 0.32
13.61–14.64
5.37 6 0.17
5.14–5.78
7.42 6 0.24
7.17–7.91
15.58 6 0.32
15.21–16.16
11.69 6 0.32
11.23–12.30
6.93 6 0.23
6.49–7.25
7.22 6 0.16
6.92–7.51
9.13 6 0.23
8.76–9.52
11.81 6 0.53
11.09–12.60
4.95 6 0.22
4.60–5.30
10.92 6 0.44
10.23–11.58
1.82 6 0.07
1.69–1.92
2.26 6 0.14
2.02–2.43
3.53 6 0.14
3.37–3.82
139.4 6 2.9 (8)
134–142
269.4 6 5.6 (8)
261–277
130.0 6 3.9 (8)
125–136
35.5 6 0.7
34–36
21.1 6 0.7
20–22
72.2 6 4.6
66–79
COMMENTS—Because this species was the best known of the
Luzon Megapomys for many years, the few scattered
specimens from other parts of Luzon were often tentatively,
but incorrectly, referred to this species in collections and in
some publications (e.g., Danielsen et al., 1994; Heaney et al.,
1998). We have examined the holotype of A. major
Miller 1910, and agree with Musser (1982) that it is not
distinguishable from A. datae and should be treated as a junior
synonym.
Apomys abrae (Sanborn, 1952)
Rattus (Apomys) abrae Sanborn, 1952: 133.
Apomys abrae. Johnson 1962. First use of current name combination.
16
F (n = 10)
33.94 6 0.55
33.24–34.76
5.89 6 0.23
5.42–6.21
18.19 6 0.23 (9)
17.87–18.63
13.99 6 0.31
13.39–14.46
13.76 6 0.24
13.38–14.23
5.28 6 0.38
4.75–5.87
7.38 6 0.16
7.16–7.66
15.14 6 0.37
14.61–15.89
11.72 6 0.34
11.07–12.08
6.78 6 0.26
6.48–7.26
7.17 6 0.26
6.77–7.50
9.18 6 0.23
8.80–9.59
11.34 6 0.36
10.87–12.07
4.97 6 0.22
4.66–5.42
10.80 6 0.28
10.28–11.30
1.81 6 0.08
1.70–1.93
2.23 6 0.07
2.12–2.32
3.55 6 0.20
3.22–3.88
137.8 6 4.9 (8)
133–149
261.3 6 6.9 (8)
256–276
123.5 6 2.8 (8)
121–127
34.5 6 0.7
33–35
20.7 6 1.1
19–22
70.7 6 5.9
63–82
Mt. Amuyao, Mountain Prov.
M (n = 10)
35.02 6 0.92
33.58–36.58
6.21 6 0.26
5.91–6.71
18.15 6 0.39 (9)
17.60–18.84
14.34 6 0.25
13.85–14.66
14.66 6 0.49
14.03–15.52
5.15 6 0.32
4.58–5.57
7.49 6 0.17
7.26–7.73
16.01 6 0.62
15.16–17.09
11.31 6 0.37
10.85–11.84
6.80 6 0.19
6.53–7.18
7.34 6 0.26
6.96–7.81
9.38 6 0.40
8.95–10.21
11.64 6 0.19
11.38–12.00
5.02 6 0.15
4.79–5.28
10.55 6 0.40
9.77–11.02
1.83 6 0.07
1.74–2.01
2.17 6 0.10
2.01–2.30
3.41 6 0.16
3.12–3.59
138.7 6 7.2
127–151
268.9 6 14.3
250–292
130.2 6 7.9
121–141
37.0 6 1.1
35–38
20.6 6 0.5
20–21
77.5 6 6.4
68–88
F (n = 10)
35.07 6 0.47
34.46–35.64
6.21 6 0.18
5.90–6.52
18.16 6 0.40
17.64–18.73
14.34 6 0.21
14.11–14.72
14.90 6 0.45
14.42–15.91
5.20 6 0.26
4.86–5.65
7.45 6 0.17
7.20–7.69
15.97 6 0.21
15.71–16.36
11.57 6 0.20
11.31–11.91
6.86 6 0.18
6.65–7.21
7.28 6 0.22
6.91–7.62
9.52 6 0.27
9.10–9.89
11.83 6 0.27
11.46–12.29
5.13 6 0.18
4.88–5.44
10.81 6 0.30
10.40–11.22
1.83 6 0.09
1.71–1.95
2.21 6 0.08
2.13–2.40
3.55 6 0.26
3.28–3.96
139.9 6 5.2
132–147
271.5 6 5.3
262–278
131.6 6 4.2
128–142
35.8 6 1.3
34–38
20.5 6 0.7
20–22
79.2 6 10.2
65–90
HOLOTYPE—FMNH 62750, young adult male, obtained 14
May 1946. Field number H. H. Hoogstraal 460. Prepared as
stuffed skin plus skull. Measurements in Table 2.
TYPE LOCALITY—Philippines: Luzon Island: Abra Province:
Massisiat, 3500 feet [ca. 1100 m] (approximately 17.583uN,
120.833uE; our estimate from topographic maps). Taken in
‘‘thick growth along mountain creek’’ (from specimen tag).
SPECIMENS EXAMINED (n 5 183)—LUZON ISLAND: Abra Prov.:
Massisiat, 3500 ft [ca. 1100 m] (FMNH 62749; 62750).
Benguet Prov.: Baguio (USNM 151510, 399580); Baguio, 3000 ft [ca.
900 m] (USNM 399573–399577); Baguio, 3600 ft [ca. 1100 m] (USNM
399579); Baguio, 4000 ft [ca. 1200 m] (USNM 399578); Haight’s-in-theOaks, 7000 ft [ca. 2100 m] (USNM 151507–151509, 151530, 261170);
near Baguio (MCZ 35034, 35035); near Baguio, Mt. Santo Tomas
(AMNH 242099, 242100; FMNH 202181); Sablan (FMNH 92763, 92764).
TABLE 2.
Extended.
Apomys datae
Mt. Pulag, Benguet Prov.
Apomys abrae
Massisiat, Abra Prov.
M (n = 10)
F (n = 10)
M-holotype
FMNH 62750
35.68 6 0.61
34.65–36.59
6.23 6 0.28
5.80–6.74
18.57 6 0.47
18.12–19.50
14.69 6 0.41
14.20–15.42
14.75 6 0.45
14.21–15.65
5.26 6 0.19
4.95–5.51
7.63 6 0.26
7.38–8.23
16.59 6 0.45
15.93–17.38
11.64 6 0.32
11.01–12.14
7.09 6 0.25
6.71–7.46
7.49 6 0.29
7.00–7.93
9.72 6 0.32
9.30–10.28
11.86 6 0.29
11.54–12.28
5.23 6 0.29
4.72–5.65
11.13 6 0.42
10.57–11.95
1.92 6 0.13
1.71–2.13
2.24 6 0.08
2.08–2.40
3.63 6 0.22
3.22–3.94
143.8 6 6.7
131–155
273.9 6 9.2
261–292
130.1 6 4.0
122–137
36.8 6 1.0 (9)
35–38
22.1 6 0.6
21–23
87.8 6 10.6
70–105
35.19 6 0.91
33.90–37.04
6.00 6 0.22
5.73–6.31
18.45 6 0.51
17.68–19.47
14.53 6 0.27
14.11–14.92
14.84 6 0.58
13.54–15.41
5.47 6 0.22
5.18–5.96
7.46 6 0.38
6.89–7.95
16.24 6 0.60
15.40–17.19
11.62 6 0.36
10.99–12.00
7.10 6 0.28
6.48–7.57
7.41 6 0.27
7.10–7.93
9.51 6 0.30
9.05–9.94
11.72 6 0.44
11.10–12.37
5.00 6 0.26
4.57–5.44
11.14 6 0.37
10.55–11.66
1.88 6 0.09
1.74–2.03
2.29 6 0.13
2.08–2.50
3.56 6 0.24
3.16–3.92
139.7 6 7.4
132–153
268.5 6 11.1
255–287
128.8 6 6.3
121–136
35.9 6 1.3
35–39
21.1 6 1.0
20–22
77.2 6 6.2 (9)
70–86
31.09
—
5.50
—
—
—
—
—
12.59
—
4.60
—
6.39
—
13.62
—
10.84
—
6.69
—
6.75
—
7.79
—
10.62
—
4.23
—
10.43
—
1.93
—
2.06
—
3.01
—
125
—
255
—
130
—
34
—
–
—
—
—
Mt. Data, Mountain Prov.
F (n = 1)
M (n = 2)
31.70
—
—
—
—
—
—
—
13.03
—
4.75
—
6.55
—
14.17
—
—
—
6.62
—
—
—
8.62
—
—
—
—
—
—
—
1.78
—
2.09
—
3.15
—
139
—
278
—
139
—
35
—
—
—
—
—
32.64 6 0.90
32.00–33.27
5.83 6 0.25
5.65–6.00
17.42 (1)
—
13.73 6 0.88
13.10–14.35
13.39 6 0.22
13.23–13.54
5.07 6 0.04
5.04–5.10
7.09 6 0.27
6.90–7.28
15.20 6 0.12
15.11–15.28
10.75 6 0.77
10.20–11.29
6.68 6 0.11
6.60–6.75
6.97 6 0.04
6.94–7.00
8.68 6 0.61
8.25–9.11
11.36 6 0.34
11.12–11.60
4.82 6 0.45
4.50–5.13
10.03 6 0.69
9.54–10.52
1.71 6 0.14
1.61–1.81
1.99 6 0.04
1.96–2.01
3.10 6 0.07
3.05–3.15
136 (1)
—
271 (1)
—
135 (1)
—
36 (1)
—
21 (1)
—
72 (1)
—
Ilocos Norte Prov.: Mt. Simminublar (FMNH 92753–92756, 92758–92760,
92762); Mt. Simminublar, 4000 ft [ca. 1200 m] (FMNH 92757); Mt.
Simminublar, 4300 ft [ca. 1300 m] (FMNH 92761); Mt. Simminublar, 4350 ft [ca. 1300 m] (FMNH 92752); Tagudin (AMNH 252473).
Kalinga Prov.: Balbalan Munic.: Balbalasang Brgy.: Balbalasang,
900 m (FMNH 169182, 169183); Balbalasang Brgy.: Magdallao, 1600 m
(FMNH 167245, 167254, 167258, 167259, 167261–167262, 167273–
167277, 167285–167287, 167292, 167294, 167299–167301, 167303,
167342–167344, 167346, 167347, 167349, 167355, 167356, 167358,
167361, 167367); Balbalan Munic.: Balbalasang Brgy.: Mapga, 1050 m
(FMNH 169021–169067, 169069, 169070, 170904–170930).
Mountain Prov.: 0.3 km N Barlig Munic. Hall, 1730 m (FMNH
193532); 0.4 km N Barlig Munic. Hall, 1790 m (FMNH 193533, 193534,
193867, 193868); 0.6 km N Barlig Munic. Hall, 1800 m (FMNH
193535–193547, 193869–193876); Mt. Data (FMNH 62738); Mt. Data,
5300 ft [ca. 1600 m] (FMNH 62719, 62728); Mt. Data, 6500 ft [ca.
2000 m] (FMNH 62700); Mt. Data, 7500 ft [ca. 2300 m] (FMNH 62723–
Balbalasang, 900 m, Kalinga Prov.
F (n = 4)
32.40 6 0.44
31.80–32.74
5.69 6 0.19
5.54–5.96
17.02 6 0.30 (3)
16.84–17.37
13.89 6 0.35
13.52–14.35
13.67 6 0.40
13.26–14.11
5.07 6 0.21
4.88–5.36
6.92 6 0.21
6.67–7.18
14.60 6 0.56
14.10–15.19
11.13 6 0.20
10.86–11.30
6.94 6 0.08
6.85–7.01
7.18 6 0.12
7.08–7.33
8.48 6 0.19
8.31–8.75
10.99 6 0.15
10.83–11.18
4.82 6 0.34
4.44–5.14
10.63 6 0.43
10.09–11.03
1.80 6 0.03
1.77–1.83
2.01 6 0.05
1.95–2.05
3.17 6 0.21
2.90–3.36
133.0 6 3.6 (3)
129–136
267.7 6 5.9 (3)
261–272
134.7 6 3.1 (3)
132–138
35.0 6 0.0 (3)
35
20.7 6 0.6 (3)
20–21
68.0 6 8.5 (2)
62–74
M (n = 1)
F (n = 1)
32.39
—
6.09
—
16.74
—
13.29
—
14.05
—
5.09
—
6.82
—
14.93
—
11.00
—
6.54
—
7.13
—
8.83
—
11.77
—
4.67
—
10.47
—
1.83
—
2.08
—
3.13
—
—
—
—
—
137
—
35
—
21
—
—
—
32.55
—
5.50
—
16.81
—
13.50
—
13.64
—
4.79
—
7.05
—
14.66
—
11.26
—
7.09
—
7.14
—
8.33
—
11.68
—
4.96
—
10.57
—
1.81
—
2.05
—
3.22
—
—
—
—
—
129
—
35
—
21
—
—
—
62724, 62726); 8000 ft [ca. 2400 m] (FMNH 62739, 62740); Mt. Data:
0.9 km N, 1.75 km E south peak, 2228 m (FMNH 188294–188297,
188483); Mt. Data: 1.0 km N, 1.25 km E south peak, 2231 m (FMNH
188292, 188293, 188437).
EMENDED DIAGNOSIS AND DESCRIPTION—A medium-sized
Megapomys, averaging smaller than A. datae in nearly all
measurements (Tables 2, 3). The tail is long relative to the
head and body, with TV/HBL of our sampled populations
averaging 97–101%. The dorsal pelage is a rich and dark
brown, with little or no rusty-orange tint (Fig. 1C). The fur on
the dorsal surface of the forepaws and hind feet is white or
with very few scattered dark hairs (vs. having dark hairs
extending over much of the tops of the feet). Apomys abrae
rarely have any black hairs on the ventral surface of the tail,
17
FIG. 10.
Ventral surface of the right hind feet of Apomys subgenus Megapomys, all shown to the same scale.
and the scales are white (when clean). The hind feet are
proportionately somewhat narrow, the toes are long, and the
plantar pads are relatively small and well separated
(Fig. 10A). The ventral surface of the hind foot typically has
little pigment. Specimens from Abra and Ilocos Norte have
dorsal pelage much paler than specimens from Benguet,
18
Kalinga, or Mountain province, approaching sandy-brown
with orange tints. We suspect this is due to fading in these
older specimens (1940s–1960s); field surveys in Abra and
Ilocos Norte are needed to test this hypothesis.
The cranium of A. abrae (Fig. 16) is one of the smallest within
Megapomys, with a moderately short and slender rostrum,
rounded braincase, narrow palate, short maxillary toothrow,
and short postpalatal region (Tables 2, 3). Its small size is clearly
apparent on the first axis of the PCA of craniodental
measurements, on which A. abrae and A. brownorum sp. nov.
have the lowest scores (Fig. 6A). The foramen in the bulla for
the stapedial artery is lacking in A. abrae (Fig. 5A); that is, it has
the ‘‘abrae pattern’’ (see Carotid Circulatory Patterns above).
The interparietal bone is variable in shape, but usually oval and,
anteroposteriorly, relatively narrow. The mandible (Fig. 16C) is
relatively small and slender, with a relatively short coronoid
process, narrow angular process, and deeply concave margin
between the condylar and angular processes.
The karyotype of A. abrae, based on two males from
Kalinga Province (FMNH 169051, 169065), has 2n 5 44, FN $
54 (Fig. 8B). The autosomal complement includes two pairs of
large submetacentric, two pairs of small to medium-sized
subtelocentric, one pair of very small metacentric, and 16 pairs
of telocentric (or subtelocentric) chromosomes. Both the large
X chromosome and the very small Y are telocentric. This
karyotype was mistakenly reported earlier as representing A.
datae (Rickart & Heaney, 2002). The two species have very
similar karyotypes, although there may be minor variation in
the number and size of secondary arms on some autosomes. In
contrast, both A. zambalensis sp. nov. and A. banahao sp. nov.
have submetacentric X chromosomes and FN $ 58; the
former has 2n 5 44 and the latter 2n 5 48.
To assess geographic variation among individuals we refer
to this species, we conducted a PCA of the 18 craniodental
measurements in Tables 2 and 3. This included specimens
from Mt. Data (Mountain Province), from three elevations on
Mt. Bali-it (Kalinga Province), and from Mt. Amuyao.
Because the specimens from Abra (including the holotype)
and Ilocos Norte provinces have damaged skulls, they could
not be included in this analysis. The first component, which
accounted for 34% of the variance, loaded heavily on most
measurements, with the exception of orbitotemporal length,
braincase height, and breadth of M1 (Table 6). The second
component, which accounted for 15% of the variance, loaded
most heavily on length of the molar toothrow, palatal breadth
at M1, diastema length, braincase height, breadth of M1, and
width of the zygomatic plate. The remaining components had
eigenvalues below 2.0 and were not interpretable. A plot of
individual scores on PC1 and PC2 (Fig. 17) shows a high
degree of overlap among the five groups, with no evident
means to distinguish among them. Because we can detect no
apparent differences among the crania of any of the specimens
listed above as A. abrae, and because the cyt b data (Fig. 7)
show specimens from Abra and Ilocos Norte provinces to be
very similar to samples from Mt. Data and Mt. Amuyao, we
conclude that these represent a single species.
COMPARISONS—As noted above, A. abrae differs from A.
datae in being smaller overall, usually with little or no overlap
in the features measured (Tables 2, 3), but the tail is
proportionately longer (in our sampled populations, averaging
97–101% vs. 89–95% in A. datae), and a plot of relative length
of the tail and weight (Fig. 12A) shows little overlap. The
dorsal fur of A. abrae (Fig. 1C) has little of the rusty, slightly
orange tint that A. datae (Fig. 1B) typically possesses. The tail
of A. abrae is white ventrally, whereas scattered black hairs are
often present on A. datae, and the scales are pale gray, not
white. The toes of A. abrae are relatively longer and narrower
than those of A. datae, the plantar pads are smaller and more
widely separated than in A. datae, and much less pigment on
the ventral surface is present than in A. datae (Fig. 10B). The
cranium of A. abrae is consistently smaller than that of A.
datae, with little overlap in zygomatic breadth, mastoid
breadth, nasal length, rostral depth, rostral length, width of
the zygomatic plate, and postpalatal length (Tables 2, 3).
Bivariate plots of zygomatic breadth and mastoid breadth
(Fig. 12B) and of rostral length and rostral depth (Fig. 12C)
show the differences clearly. The interparietal bone of A. abrae
is usually anteroposteriorly narrower than that of A. datae.
The mandible of A. datae is larger and more robust, as
described under that species.
Musser (1982) noted that morphological differences between A. abrae and A. sacobianus are slight in most respects
and suggested that they might be conspecific. With our larger
sample of A. abrae, it is clear that the holotype and still only
known specimen of A. sacobianus is larger in all respects and
differs in having a narrow line of dark hairs reaching to the
base of the toes on the dorsal surface of the forefeet (vs. white
fur only). The cranium is generally larger and more robust
with a deeper and wider rostrum, but the palate is narrower.
Additional details are discussed in the A. sacobianus species
account below.
DISTRIBUTION—Apomys abrae occurs widely over the Central
Cordillera of northern Luzon, with records from Benguet to
Ilocos Norte (Figs. 3, 18). It has been recorded from 950 to
2200 m elevation (Fig. 15) in habitats ranging from mixed grass
and shrubs beneath pines to dense montane rain forest.
Compared with A. datae, with which it overlaps broadly, it
often occurs at lower elevations and in relatively drier and more
open habitats, including, but not restricted to, pine forest with
broad-leafed undergrowth (Heaney et al., 1998, 2003; Rickart et
al., 2007, 2011). Additional surveys are needed to determine its
distribution at lower and middle elevations in Abra, Apayao,
Ilocos Norte, and Ilocos Sur provinces in the Cordillera and at
the boundary of the Central Cordillera and the Caraballo
Mountains, where A. sierrae sp. nov. occurs.
COMMENTS—Given the conspicuous and easily recognized
diagnostic features of this species, it is remarkable that the
mitochondrial data (Fig. 7) fail to separate A. abrae and A.
datae. We hypothesize that this is an instance of introgression
because analysis of some nuclear genes reveals a subsample of
individuals to be reciprocally monophyletic and not sister-species
(S. J. Steppan, unpubl. data); details will be published elsewhere.
Apomys gracilirostris Ruedas, 1995
Apomys gracilirostris Ruedas, 1995: 305.
HOLOTYPE—NMP 3482. Adult male collected 12 June 1992.
Field number NMP/CMNH 1136. Prepared as stuffed skin plus
skull.
TYPE LOCALITY—Philippines: Mindoro Island: Mindoro
Occidental Province: San Teodoro Munic.: North Ridge
approach to Mt. Halcon, ca. 1580 m, ca. 13u169480N,
121u599190E.
SPECIMENS EXAMINED (n 5 2): MINDORO ISLAND: Mindoro
Occidental Prov.: San Teodoro Munic.: North Ridge approach to Mt.
Halcon (NMP 3476, 3478).
EMENDED DIAGNOSIS AND DESCRIPTION—The pelage of this
species both dorsally and ventrally is dark brown, but slightly
paler ventrally (Fig. 1A). The tail is proportionately longer
than in other Megapomys, averaging about 105% of head and
19
TABLE 3.
Cranial and external measurements (mean 6 1 S.D. and range) of Apomys abrae, A. gracilirostris, A. sacobianus, and A. brownorum.
Apomys abrae
Balbalasang, 1100 m,
Kalinga Prov.
Measurement
M (n = 10)
33.47 6 0.59
32.62–34.32
5.72 6 0.15
5.50–6.01
Zygomatic breadth
17.41 6 0.45
16.87–18.13
Mastoid breadth
13.89 6 0.28 (9)
13.45–14.30
Nasal length
13.82 6 0.34
13.24–14.15
5.05 6 0.27
4.57–5.44
Rostral depth
7.23 6 0.15
7.06–7.56
Rostral length
14.86 6 0.29
14.42–15.28
11.13 6 0.35
10.57–11.82
Maxillary toothrow
6.93 6 0.25
length
6.55–7.40
7.27 6 0.15
Labial palatal breadth at
1
7.07–7.48
M
Diastema length
9.04 6 0.26
8.69–9.42
Postpalatal length
11.77 6 0.32
11.24–12.35
5.09 6 0.14 (9)
Lingual palatal breadth
4.90–5.34
at M3
Braincase height
10.52 6 0.36
10.07–11.12
1.82 6 0.04
Breadth of M1
1.76–1.90
2.15 6 0.09
1.94–2.27
Width of zygomatic plate 3.31 6 0.11
3.08–3.44
Length of head and body 134.6 6 5.6 (9)
124–141
Total length
269.6 6 6.8 (9)
258–283
Length of tail vertebrae
135.9 6 6.7
125–144
Length of hind foot
37.0 6 0.7 (9)
36–38
Length of ear
22.0 6 0.5 (9)
21–23
Weight (g)
72.6 6 4.7 (9)
66–79
F (n = 11)
32.86 6 0.67
31.73–34.28
5.61 6 0.15
5.42–5.95
17.00 6 0.34
16.53–17.69
13.73 6 0.15
13.51–14.03
13.61 6 0.34
13.22–14.29
5.02 6 0.23
4.61–5.41
7.10 6 0.19
6.86–7.44
14.52 6 0.42
13.91–15.23
11.14 6 0.26
10.72–11.57
6.82 6 0.21
6.56–7.23
7.06 6 0.19
6.72–7.33
8.85 6 0.36
8.14–9.32
11.55 6 0.20
11.20–11.87
4.89 6 0.17
4.44–5.07
10.46 6 0.21
10.09–10.70
1.79 6 0.09
1.61–1.91
2.09 6 0.07
1.99–2.24
3.23 6 0.15
2.93–3.49
131.4 6 5.0 (10)
121–137
262.6 6 8.6
242–275
130.8 6 6.3 (10)
121–140
35.8 6 1.4 (10)
34–39
21.6 6 0.5 (10)
21–22
66.7 6 6.5 (10)
59–76
Balbalasang, 1600 m,
Kalinga Prov.
M (n = 2)
33.14 6 0.87
32.52–33.75
5.69 6 0.13
5.59–5.78
16.83 6 0.18
16.70–16.95
13.99 6 0.06
13.95–14.03
13.52 6 0.06
13.48–13.56
5.31 6 0.22
5.15–5.46
7.25 6 0.07
7.20–7.30
14.54 6 0.10
14.47–14.61
11.51 6 0.57
11.10–11.91
7.05 6 0.06
7.00–7.09
7.20 6 0.03
7.18–7.22
8.72 6 0.16
8.61–8.83
11.44 6 0.23
11.28–11.60
4.91 6 0.21
4.76–5.05
10.86 6 0.08
10.80–10.91
1.80 6 0.02
1.78–1.81
2.15 6 0.04
2.12–2.18
3.20 6 0.13
3.10–3.29
131.5 6 2.1
130–133
259.0 6 1.4
258–260
127.5 6 0.7
127–128
36.0 6 0.0
36
23.0 6 1.4
22–24
71.5 6 3.5
69–74
body length (Ruedas, 1995), and is thicker at the base than in
other species. The tail is dark brown both dorsally and
ventrally, slightly paler ventrally, and often white at the tip.
The hind feet are shorter and broader than those of other
Megapomys, with proportionately larger plantar pads and a
hallux that reaches to the top or slightly beyond the top of the
adjacent plantar pad; the ventral surface is moderately heavily
pigmented except for the pads (Fig. 10J; Table 3). The upper
incisors are laterally compressed relative to depth, 1.56–
1.76 mm at the tip; the lower incisors are unpigmented and
elongate (Fig. 19). The rostrum is long and slender and turns
up slightly near the tip. The braincase is more globose than in
other Megapomys. The maxillary molars are narrow and the
20
F (n = 3)
33.02 6 0.25
32.74–33.20
5.60 6 0.16
5.46–5.78
17.00 6 0.47 (2)
16.66–17.33
13.53 6 0.26
13.29–13.81
13.78 6 0.28
13.47–13.99
5.24 6 0.35
4.91–5.60
7.09 6 0.24
6.83–7.30
14.74 6 0.26
14.48–15.00
10.95 6 0.34
10.63–11.31
6.69 6 0.07
6.61–6.74
6.85 6 0.09
6.79–6.95
9.00 6 0.30
8.65–9.18
11.54 6 0.10
11.42–11.60
4.93 6 0.38
4.61–5.35
10.43 6 0.14
10.30–10.58
1.65 6 0.06
1.60–1.72
2.12 6 0.02
2.10–2.14
3.36 6 0.29
3.03–3.58
132.7 6 1.2
132–134
262.7 6 4.6
260–268
130.0 6 3.5
128–134
35.7 6 0.6
35–36
22.7 6 0.6
22–23
57.0 6 4.6
53–62
Mt. Amuyao,
Mountain Prov.
M (n = 5)
32.45 6 0.37
32.00–32.97
5.60 6 0.15
5.47–5.86
16.56 6 0.48
16.04–17.17
13.25 6 0.33
12.88–13.74
13.48 6 0.24
13.24–13.83
5.07 6 0.29
4.76–5.47
6.77 6 0.15
6.62–7.02
14.57 6 0.22
14.33–14.92
11.24 6 0.29
10.80–11.50
6.69 6 0.15
6.51–6.87
7.06 6 0.25
6.82–7.43
8.86 6 0.36
8.54–9.47
10.86 6 0.13
10.66–10.99
4.54 6 0.23
4.29–4.78
10.42 6 0.33
9.92–10.71
1.84 6 0.03
1.80–1.87
1.96 6 0.07
1.86–2.02
3.09 6 0.09
3.00–3.21
126.2 6 4.0
122–132
254.0 6 8.6
242–265
127.8 6 4.9
120–133
34.4 6 0.5
34–35
21.4 6 0.5
21–22
56.6 6 5.9
50–66
F (n = 5)
33.42 6 0.94 (4)
32.16–34.40
5.55 6 0.07
5.43–5.60
16.65 6 0.35
16.19–16.98
13.38 6 0.12 (4)
13.27–13.53
13.93 6 0.45
13.15–14.33
5.03 6 0.24
4.80–5.34
6.98 6 0.22
6.71–7.28
14.99 6 0.46
14.22–15.37
11.50 6 0.19
11.31–11.81
6.76 6 0.09
6.65–6.89
7.05 6 0.19
6.79–7.30
9.10 6 0.16
8.93–9.34
11.25 6 0.76 (4)
10.34–12.15
4.96 6 0.17
4.70–5.16
10.33 6 0.17 (4)
10.08–10.42
1.83 6 0.05
1.79–1.89
2.05 6 0.10
1.89–2.12
3.03 6 0.14
2.90–3.24
133.6 6 4.7
126–137
264.2 6 7.8
252–272
130.6 6 3.9
126–135
34.2 6 1.1
33–35
21.2 6 0.4
21–22
62.6 6 5.2
54–68
toothrow is short. The postpalatal region is long. A foramen is
present in the bulla for the stapedial artery (the ‘‘datae
pattern’’). The interparietal bone is variable in shape but is
usually moderately wide anteroposteriorly. The mandible
(Fig. 19C) is long and slender, with a short coronoid process
and a short, blunt angular process (see Ruedas [1995] for
additional details). No other species of rodent on Mindoro is
similar in size and overall morphology.
COMPARISONS—Apomys gracilirostris differs from A. datae
in having darker pelage dorsally and much darker pelage
ventrally, with a proportionately longer and thicker tail and
shorter and broader hind feet. The crania are of similar total
length, but that of A. datae is more robust overall, with a
TABLE 3.
Apomys abrae
Apomys gracilirostris
Mt. Simminublan,
Ilocos Norte Prov.
Mt. Halcon, Mindoro
Island
M/F (n = 9)
F (n = 2)
32.10 6 0.46 (5)
31.43–32.58
5.48 6 0.16 (7)
5.27–5.71
16.65 6 0.52 (4)
15.93–17.17
13.17 6 0.83 (3)
12.21–13.65
13.18 6 0.50 (8)
12.18–13.70
5.08 6 0.19 (8)
4.89–5.52
6.85 6 0.17 (7)
6.62–7.11
14.22 6 0.43 (7)
13.60–14.68
11.24 6 0.40 (4)
10.81–11.77
6.59 6 0.27 (7)
6.19–6.99
6.79 6 0.35 (5)
6.42–7.31
8.47 6 0.36 (7)
7.98–8.98
10.99 6 0.53 (4)
10.26–11.42
4.51 6 0.08 (2)
4.45–4.56
10.23 6 0.66 (3)
9.50–10.76
1.72 6 0.10 (7)
1.58–1.85
2.06 6 0.09 (7)
1.93–2.23
3.08 6 0.19 (8)
2.84–3.33
—
—
—
—
—
—
—
—
—
—
—
—
33.85 6 0.71
33.34–34.35
6.02 6 0.21
5.87–6.17
17.57 6 0.20
17.43–17.71
14.48 6 0.04
14.45–14.51
14.42 6 0.28
14.22–14.62
4.77 6 0.13
4.67–4.86
7.00 6 0.11
6.92–7.08
16.08 6 0.55
15.69–16.47
10.53 6 0.23
10.36–10.69
6.25 6 0.09
6.19–6.31
7.33 6 0.01
7.32–7.34
9.52 6 0.54
9.13–9.90
11.53 6 0.27
11.34–11.72
5.27 6 0.01
5.26–5.27
10.71 6 0.71
10.20–11.21
1.76 6 0.01
1.75–1.77
1.74 6 0.03
1.72–1.76
3.28 6 0.12
3.19–3.36
—
—
—
—
147.0 6 8.5
141–153
36.0 6 0.0
36
18.0 6 0.0
18
—
—
Extended.
Apomys sacobianus
Apomys brownorum
Sacobia River,
Pampanga Prov.
M-holotype
304352
USNM
Mt. Tapulao, 2024 m, Zambales Prov.
M-holotype
183524
FMNH
34.29
—
6.02
—
17.97
—
14.04
—
13.91
—
5.70
—
7.96
—
15.04
—
11.73
—
6.92
—
7.20
—
8.55
—
11.88
—
4.10
—
10.30
—
1.97
—
2.27
—
3.46
—
141
—
290
—
149
—
40
—
22
—
—
—
heavier rostrum, broader and more squarish braincase,
broader zygomatic plate and zygomatic arches, broader
incisive foramina, and a longer toothrow. Both species have
the ‘‘datae pattern’’ of carotid circulatory pattern (Fig. 5). The
mandible of A. gracilirostris is similar in length to that of A.
datae but is more slender, with the bony sheath of the anterior
portion of the mandible extending less far onto the incisor.
The coronoid process of the mandible is shorter and less
pointed than in A. datae, and the angular process is shorter
and blunter.
DISTRIBUTION—Apomys gracilirostris is currently known
only from 1250 to 1950 m on the North Ridge of Mt. Halcon
(Fig. 18). This species should be sought widely in the
33.57
—
5.75
—
17.54
—
14.01
—
13.62
—
4.86
—
7.06
—
14.92
—
11.59
—
6.53
—
6.87
—
9.44
—
11.66
—
4.80
—
11.13
—
1.76
—
2.13
—
2.70
—
135
—
250
—
115
—
34
—
21
—
71
—
M (n = 10)
33.55 6 0.91
32.41–34.85
5.65 6 0.13
5.38–5.87
17.44 6 0.45
16.69–18.09
14.09 6 0.33
13.63–14.70
13.88 6 0.49
12.90–14.63
5.03 6 0.23
4.66–5.48
7.05 6 0.17
6.73–7.36
15.12 6 0.54
14.27–15.83
11.28 6 0.33
10.63–11.70
6.59 6 0.17
6.37–6.81
6.82 6 0.20
6.56–7.09
9.44 6 0.29
8.79–9.77
11.51 6 0.42
11.03–12.10
4.87 6 0.26
4.46–5.29
10.65 6 0.38
10.12–11.13
1.69 6 0.05
1.63–1.76
2.09 6 0.08 (9)
1.94–2.18
2.71 6 0.09
2.56–2.82
134.3 6 5.3 (9)
125–140
246.9 6 6.3 (9)
235–255
112.6 6 2.7 (9)
110–116
33.8 6 1.3
32–36
21.5 6 0.5
21–22
77.1 6 5.5
69–84
F (n = 5)
32.43 6 0.33
31.96–32.75
5.60 6 0.13
5.46–5.78
17.14 6 0.24
16.88–17.45
13.91 6 0.26 (4)
13.69–14.28
13.17 6 0.31
12.74–13.58
4.99 6 0.16
4.80–5.16
6.79 6 0.16
6.54–6.97
14.65 6 0.25
14.28–14.93
11.14 6 0.34
10.81–11.58
6.60 6 0.18
6.38–6.80
6.75 6 0.10
6.57–6.83
8.89 6 0.16
8.67–9.09
10.95 6 0.18
10.75–11.21
4.69 6 0.30
4.35–5.05
10.72 6 0.34
10.32–11.25
1.71 6 0.06
1.65–1.79
2.03 6 0.07
1.92–2.08
2.55 6 0.20
2.23–2.78
128.0 6 4.6
123–135
238.6 6 6.2
230–247
110.6 6 2.6
107–114
33.4 6 1.5
31–35
21.6 6 0.5
21–22
69.4 6 8.9
60–82
mountains that make up the central core of Mindoro, at
elevations from 700 m to more than 2000 m, areas from which
no data on small mammals are currently available. The long
tail and short, broad hind foot implies to us that it could be
partially arboreal.
COMMENTS—The combination of the dark pelage, long tail,
short and broad hind feet, and slender rostrum, globose
braincase, and narrow incisors easily distinguish A. gracilirostris
from all other Megapomys. The long tail and slender rostrum are
characters shared with the subgenus Apomys, which suggests
that they represent primitive character states, whereas the short
tail and robust rostrum of the remaining species of Megapomys
might represent shared, derived characters.
21
analysis of log-transformed measurements of adult Apomys abrae and
A. datae (see Fig. 13 and Methods).
Principal component
Variable
FIG. 11. Results of the principal components analysis of Apomys
datae (see text and Table 4) based on specimens included in Table 2. 1
5 Mt. Data, Mountain Province; 2 5 Mt. Bali-it and vicinity,
Kalinga Province; 3 5 Mt. Amuyao, Mountain Province; 4 5 Mt.
Pulag, Benguet Province.
HOLOTYPE—USNM 304352. Adult male, collected 16 August
1956. Field number D. H. Johnson 8555. Prepared as stuffed
skin plus skull. Measurements in Table 3.
TYPE LOCALITY—Philippine Islands: Luzon: Pampanga
Province: Clark Air Base, Sacobia River, in a narrow forested
canyon of the Sacobia River ‘‘just above the point where it
analysis of log-transformed measurements of adult Apomys datae (see
Fig. 11 and Methods).
Principal component
0.879
0.454
Zygomatic breadth
0.725
Mastoid breadth
0.788
Nasal length
0.767
0.036
Rostral depth
0.730
Rostral length
0.778
0.381
0.591
0.581
Diastema length
0.611
Postpalatal length
0.693
3
0.431
Lingual palatal breadth at M
Braincase height
0.495
0.507
Breadth of M1
0.309
0.358
Eigenvalue
6.451
35.84
22
3
4
0.144
0.094
0.071
0.017
0.035
0.455
0.122
0.059
20.005
20.645
20.400
0.455
0.051
0.315
20.159
20.745
20.046
20.014
1.730
9.61
0.123
20.344
20.135
20.192
0.033
0.557
20.050
0.068
20.281
0.274
0.283
0.174
0.129
0.071
20.512
0.171
20.087
0.185
1.127
6.26
0.010
20.137
0.110
20.112
20.074
0.473
20.096
20.074
0.444
20.060
20.236
0.054
20.203
20.575
0.183
0.151
0.238
0.203
1.072
5.96
SPECIMENS EXAMINED—The holotype (and only known specimen).
Apomys sacobianus Johnson, 1962: 317–319.
1
0.937
0.686
Zygomatic breadth
0.902
Mastoid breadth
0.871
Nasal length
0.843
0.241
Rostral depth
0.861
Rostral length
0.884
0.587
0.543
0.646
Diastema length
0.738
Postpalatal length
0.690
3
0.512
Braincase height
0.663
0.468
Breadth of M1
0.695
0.694
Eigenvalue
9.173
50.96
2
emerges from the foothills of the Zambales Mountains onto
the plains of Pampanga’’ (Johnson, 1962: 319).
Apomys sacobianus Johnson, 1962
Variable
1
2
3
4
0.253
0.145
20.131
20.010
0.190
0.397
0.042
0.193
20.230
20.537
20.213
0.598
0.051
0.466
20.343
20.660
20.339
0.029
1.969
10.94
0.168
20.527
20.211
20.281
0.034
0.433
20.105
0.150
20.302
0.402
0.308
0.093
0.056
20.129
20.510
0.311
20.092
0.466
1.610
8.95
0.011
20.228
0.325
20.128
20.152
0.518
0.162
20.312
0.619
20.157
20.307
0.097
20.004
20.152
0.069
20.153
0.398
0.409
1.477
8.21
EMENDED DIAGNOSIS AND DESCRIPTION—A large Megapomys, within the range of large individuals of A. datae, but
larger than A. abrae. The tail is slightly longer than the length
of head and body (149 mm/141 mm 5 106%). The dorsal
pelage is shorter and less dense than that of other Megapomys
and grayish-brown rather than dark brown with red, orange,
or yellow tones. The ventral pelage is pale whitish-gray,
creamy along the midline and throat. The dorsal surfaces of
the hind feet are white. The dorsal surfaces of the forefeet have
a narrow stripe of dark hairs reaching from the forearm to the
base of the central toes. Because the holotype is a dried
museum study skin, no description of the ventral surface of the
hind feet is possible, beyond noting that they are longer than
those of most species of Megapomys (Table 3). The tail is
sharply bicolored, dark grayish-brown dorsally and nearly
white ventrally. The cranium (Fig. 20) is large and robust,
with a deep, squarish braincase and a broad, deep rostrum.
The incisive foramina are long (5.8 mm), as is the upper
toothrow (7.1 mm). The palate is narrow, with the premaxillary toothrows diverging only slightly posteriorly. The
postpalatal region is of moderate length. There is no foramen
in the bulla for the stapedial artery (the ‘‘abrae pattern’’;
Fig. 5). The interparietal bone is of moderate anteroposterior
width. The mandible (Fig. 20C) is of moderate length and is
robust overall. The coronoid process is short, sturdy, and
sharply pointed, and the angular process is deep and
moderately pointed.
COMPARISONS—Because only the holotype is known, and
USNM policy does not allow destructive sampling of holotypes,
no material is available for genetic analysis. Here, we make
comparisons to the four geographically nearest and most
morphologically similar species.
FIG. 12. Bivariate plots of measurements comparing Apomys abrae and A. datae. (A) Weight (WT) and length of tail vertebrae (TV) divided
by length of head and body (HBL). (B) Zygomatic breadth (ZB) and mastoid breadth (MB). (C) Rostral length (RL) and rostral depth (RD).
Apomys sacobianus differs from A. datae in having shorter,
relatively grayer dorsal pelage (vs. longer, softer, denser, and
dark brown), with entirely white fur on the dorsal surface of
the hind feet (vs. brown on the proximal portion). The tail is
both absolutely (Fig. 21A) and proportionately longer (106%
vs. 89–95%), and more sharply bicolored than is typical for A.
datae. The length of the hind foot is greater than recorded for
any A. datae (Fig. 21A). Apomys sacobianus has the carotid
circulatory pattern of A. abrae, lacking a foramen in the bulla
for a stapedial artery. The length of the incisive foramina is at
the upper end of the range for A. datae (5.8 vs. ca. 4.6–5.8 mm),
and the incisive foramina (Fig. 20B) are slightly narrower than
is typical for A. datae. The length of the nasals is near the
bottom of the range for A. datae (13.9 vs. 13.6–15.3 mm). The
rostrum is deeper than all but the largest A. datae (Fig. 21B),
but the rostral length is less than all but the smallest A. datae.
Braincase height is less than in most A. datae (Fig. 21B), and
diastema length is less than in all A. datae (Fig. 21C). The
datae and A. abrae (see text and Table 5) based on specimens in
Tables 2 and 3.
lingual breadth of palate at M3 is also substantially less than in
A. datae (Fig. 21C). Most other cranial measurements fall
within the range for A. datae. The shape of the interparietal
bone in the two species appears similar. The mandible
(Fig. 20C) is similar to that of A. datae, although slightly
more robust and with slightly shorter and more robust
coronoid and angular processes.
Apomys sacobianus differs from A. abrae in being larger in
all respects, with virtually no overlap (Tables 2, 3). The pelage
is longer and denser in A. abrae, with more extensive brown
tints. They have tails of similar proportional length (106% vs.
90–115% of head and body length). The tail and hind foot are
longer in A. sacobianus than in A. abrae (Fig. 21A). Both have
white fur on the dorsal surface of the hind feet, but on the
dorsal surface of the forefeet, A. sacobianus has a narrow line
of dark hairs reaching from the forearm to the base of the toes,
whereas the forefeet of A. abrae are entirely white. The
cranium is larger and more robust overall, with an especially
more robust (deeper and wider) rostrum (Fig. 21B). The
incisive foramina of the one known specimen of A. sacobianus
are narrower, and may be longer, than is typical for A. abrae,
and the postpalatal length is greater. The lingual breadth of
palate at M3 is narrower than in A. abrae (Fig. 21C), which
reflects the generally narrower palate of A. sacobianus. As
noted by Musser (1982), the carotid circulation pattern in A.
sacobianus is identical to that in A. abrae. The shape of the
interparietal bone in the two species appears similar, although
that of A. sacobianus is wider anteroposteriorly. The mandible
of A. sacobianus (Fig. 20C) is larger and slightly more robust
than that of A. abrae, with a less deeply concave posterior
margin between the condylar and angular processes.
Apomys sacobianus differs from A. zambalensis sp. nov.,
which occurs nearby in the Zambales Mountains, in having
grayish dorsal pelage (vs. rusty-orange brown) and in lacking
the stapedial artery foramen in the bullae (which is present in
all 53 A. zambalensis sp. nov. crania available). The holotype
of A. sacobianus has a hind foot length that lies at the upper
extreme of the range for A. zambalensis and a tail that is near
the upper extreme for A. zambalensis sp. nov. (Fig. 22A). The
crania differ conspicuously in several ways. Diastema length
of A. sacobianus is much less than in A. zambalensis sp. nov.,
and braincase height falls near the lower extreme of the range
for A. zambalensis sp. nov. (Fig. 22B). The length of M1 to M3
is below the lower end of the range for A. zambalensis sp. nov.,
and the lingual breadth of the palate at M3 is conspicuously
23
FIG. 14. Map showing the documented distribution of Apomys
banahao sp. nov., A. brownorum sp. nov., A. datae, and A. minganensis
sp. nov. See respective species accounts for localities. Shading on land
areas, in increasingly dark tones of gray: 0–500 m elevation; 501–
1000 m; 1001–1500 m; 1501–2000 m; and white above 2000 m.
Provincial boundaries are shown for reference.
less (Fig. 22C). Additionally, the breadth of M1 is greater in A.
sacobianus, although only slightly so (2.0 vs. 1.6–1.9 mm;
Tables 2, 3). In other cranial measures, the holotype of A.
sacobianus falls within the range of A. zambalensis sp. nov.
(Tables 2, 3). The interparietal bone of A. sacobianus is
narrower than that of A. zambalensis sp. nov. The mandible of
A. zambalensis sp. nov. is similar to that of A. sacobianus, but
the posterior margin between the condylar and angular
processes is narrower and more deeply concave.
Apomys magnus sp. nov. is substantially larger than A.
sacobianus in all features measured (Tables 3, 12) and differs
from it in the same specific details that separate A. sacobianus
and A. zambalensis sp. nov.
To further assess the extent to which A. sacobianus differs
from A. zambalensis sp. nov. and A. magnus sp. nov., we
conducted a PCA of 18 craniodental measurements of these
three species and also included A. aurorae sp. nov., which is
geographically more distant from A. sacobianus, but which is a
member of the same clade (Fig. 7). The first component,
which accounted for 45% of the total variance, loaded heavily
on all measurements except width of zygomatic plate
(Table 7). The second component, which accounted for 12%
of the variance, loaded heavily and positively on diastema
length and postpalatal length, and heavily but negatively on
interorbital breadth, palatal breadth at M1, breadth of M1,
and width of the zygomatic plate. The remaining components
had eigenvalues below 1.5 and were not interpretable. A plot
of PC1 and PC2 (Fig. 23) showed the holotype (and sole
24
FIG. 15. Documented elevational ranges of the species of the
subgenus Megapomys on Luzon. Brackets indicate regionally
sympatric species. Solid circle 5 known elevation; open circle 5
estimated elevation (see text); asterisk 5 record from Palaui Island.
known specimen) of A. sacobianus with a strongly negative
score on the first axis, indicating its small size relative to the
other included species. It lies outside of the polygons of A.
zambalensis sp. nov. and A. aurorae sp. nov., for both of which
we have good samples; because the holotype is a fully adult
animal, this suggests that the size difference is likely to remain
consistent when more specimens are obtained. Apomys magnus
sp. nov. has the highest scores on the first axis, reflecting its
large size.
On the second component, A. sacobianus had an intermediate score (Fig. 23), with most specimens of A. zambalensis
sp. nov. scoring positively and most specimens of A. aurorae
sp. nov. scoring negatively, reflecting differences in craniodental proportions that are more fully discussed below.
Apomys magnus sp. nov. scored at intermediate to negative
levels on this component, overlapping with A. sacobianus in
this respect. We conclude that this analysis supports the
recognition of all four of these species as being distinct from
each other.
DISTRIBUTION—Apomys sacobianus is currently known only
from the holotype, taken on the lower east-facing slope of the
FIG. 16. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys abrae (FMNH 62750,
holotype); scale bar 5 5 mm.
Zambales Mountains (Johnson, 1962; Fig. 18). We estimate
the elevation of the type locality as roughly 300 m (Fig. 15).
Because the species is known only from the holotype, the
extent of the distribution is uncertain. It should be sought in
the foothills of the Zambales Mountains in Pampanga, Tarlac,
and Pangasinan provinces.
COMMENTS—Because A. sacobianus is known only from the
holotype, an adult animal with moderately worn molars, the
extent of variation is unknown, and no tissues are available for
genetic study, making it impossible to adequately place this
animal in the context of the other species treated here. Musser
(1982) viewed A. sacobianus as a larger version of A. abrae but
retained it as a species to emphasize the difference in size and
to draw attention to the need for further study. We agree that
they are similar and might be closely related, but we document
here that there is indeed no overlap in cranial or external
dimensions with our large sample of A. abrae. We also note
the similarity in size with A. zambalensis, but the two differ in
their types of carotid circulatory patterns and in numerous
other cranial features, as listed above. Clearly, further study is
needed, but we agree with Musser (1982) that maintaining this
as a valid species is the best course of action. Further field
surveys and more specimens are badly needed.
abrae (see text and Table 6) based on specimens included in Tables 2
and 3. 1 5 Mt. Data, Mountain Province; 2 5 Mt. Bali-it, Kalinga
Province, 900 m; 3 5 Mt. Bali-it, Kalinga Province, 1100 m; 4 5 Mt.
Bali-it, 1600 m, Kalinga Province; 5 5 Mt. Amuyao,
Mountain Province.
Apomys (Megapomys) brownorum sp. nov.
HOLOTYPE—FMNH 183524, adult male collected on 12
January 2005 by Danilo S. Balete, field number DSB 3531.
A sample of muscle tissue was removed from the thigh in the
25
analysis of log-transformed measurements of adult Apomys abrae (see
Fig. 17 and Methods).
Principal component
Variable
1
0.784
0.412
Zygomatic breadth
0.769
Mastoid breadth
0.702
Nasal length
0.621
0.362
Rostral depth
0.832
Rostral length
0.620
0.122
0.497
0.547
Diastema length
0.391
Postpalatal length
0.763
3
0.712
Braincase height
0.234
20.039
Breadth of M1
0.726
0.507
Eigenvalue
6.105
33.92
2
3
4
0.390
20.285
20.077
20.264
0.169
0.470
0.107
0.352
0.052
20.583
20.457
0.755
0.159
0.098
20.496
20.469
20.160
20.520
2.613
14.52
0.225
20.143
20.191
20.429
0.562
20.142
20.341
0.453
0.254
0.161
0.428
0.034
0.005
20.245
20.323
0.758
0.023
20.126
1.979
10.99
0.063
0.202
20.037
0.186
0.024
0.292
20.149
0.146
0.753
0.032
20.044
0.118
20.247
20.111
0.663
20.011
20.347
20.175
1.457
8.096
field and preserved in ethanol before the specimen was
preserved in formaldehyde. In the museum, the skull was
removed and cleaned (see Methods). All parts are in good
condition. This specimen will be permanently deposited at the
NMP. Measurements in Table 3.
TYPE LOCALITY—Philippines: Luzon Island: Zambales
Province: Palauig Munic.: Barangay Salasa: Mt. Tapulao
peak, 2024 m; 15u28954.80N, 120u07910.40E (GPS reading).
PARATYPES (n 5 34)—Luzon Island: Zambales Prov.:
Palauig Munic.: Brgy. Salasa: Mt. Tapulao peak, 2024 m
(FMNH 183494–183523, 183525–183528).
ETYMOLOGY—‘‘brown’’ + ‘‘orum,’’ meaning ‘‘of the
Browns,’’ a plural noun used in the genitive. We name this
species in recognition of the long-standing support for
research on mammalian diversity by Barbara and Roger
Brown, without which our studies of Philippine mammals
would not have been possible.
DIAGNOSIS AND DESCRIPTION—A mouse with especially soft,
richly colored pelage and a relatively short tail. It is the
smallest species of Megapomys (e.g., BOL 32.4–34.9 mm, HBL
126–140 mm; Table 3). The dorsal pelage is soft, dense, and
moderately long; it is a rich dark brown, sometimes with rustyorange tints between the eye and pinna and below the pinna
and along the lower margin of the dorsal pelage (Fig. 2B). The
ventral pelage is dark gray at the base, with grayishochraceous tips. The transition between the dorsal and ventral
pelage is gradual. Dark hairs extend from the lower forelimb
onto the posterior third of the forepaws, and from the lower
hind leg over about four-fifths of the dorsal surface of the hind
foot. The hind feet are pale ventrally, with little or no pigment
(Fig. 10H). The tail is proportionately short (82–90% of HBL)
and sharply bicolored, with the dorsal surface dark grayishbrown and the ventral surface nearly white. The cranium
(Fig. 24; Table 3) is small, with a relatively slender rostrum
and zygomatic arches and a globose braincase. The incisive
foramina are short (4.8–5.2 mm) and narrow. The maxillary
26
abrae, A. gracilirostris, and A. sacobianus. See respective species
accounts for localities. Shading on land areas, in increasingly dark
tones of gray: 0–500 m elevation; 501–1000 m; 1001–1500 m; 1501–
2000 m; and white above 2000 m. Provincial boundaries are shown
for reference.
molariform toothrow is short (6.4–6.8 mm), and the toothrow
is narrow, as shown by the width of M1 (1.63–1.79 mm). The
maxillary toothrows diverge slightly posteriorly, and the
palate is lightly pitted and perforated. The bulla has no
perforation for a stapedial artery (the ‘‘abrae pattern’’;
Fig. 5A). The postpalatal region is unusually short (Table 3).
The interparietal bone is of moderate anteroposterior width
and is usually oval in shape. The mandible (Fig. 24C) is short
and rather slender, with a long, pointed coronoid process,
short angular process, and a shallowly concave margin
between the condylar and angular processes.
COMPARISONS—Apomys brownorum differs from A. datae in
being smaller in all respects, with little overlap in any
measurement (Tables 2, 3). The tail is both absolutely (110–
115 vs. 121–142 mm) and proportionately (70–88% of HBL vs.
88–103%) shorter. The pelage of A. brownorum (Fig. 2B) is
darker than that of A. datae (Fig. 1B), both dorsally and
ventrally. The hind foot is not as dark ventrally as that of A.
datae, with only a small amount of pigment on most
individuals. The foot and toes are broader than those of A.
datae (Fig. 10B,H). The skin of the rhinarium and lips of A.
brownorum is less dark. The skull of Apomys brownorum is
more slender and gracile overall, and they are easily
distinguished. The braincase of A. brownorum (Fig. 24) is
slightly more elongated and globose, the interorbital region
more constricted, and the rostrum proportionately shorter and
more gracile; the upper incisors are thinner in both dimensions, the incisive foramina are usually narrower, both the
FIG. 19. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys gracilirostris (NMP
3478); scale bar 5 5 mm.
zygomatic plate and the palate are absolutely and proportionately narrower, and the postpalatal region is shorter.
Apomys brownorum has the ‘‘abrae pattern’’ of basicranial
circulation, with no stapedial foramen in the bullae (Fig. 5A).
The interparietal bones are of similar shape. The mandible
(Fig. 24C) is shorter and more slender than that of A. datae,
with a more erect and sharply pointed coronoid process, and
processes is slightly more concave.
Apomys brownorum and A. banahao sp. nov. are generally
similar but also show consistent differences. Both species have
long, soft, and dense pelage dorsally that is dark brown, but
that of A. brownorum (Fig. 2B) is slightly paler and shorter.
Both species have ventral fur that is dark gray at the base and
quite pale near the tips, but A. brownorum is washed with pale
ochraceous, whereas A. banahao sp. nov. (Fig. 1D) is washed
with ashy gray. The tail in both species is sharply dorsoventrally bicolored; neither possesses a white tip. The tail of A.
brownorum is usually shorter than that of A. banahao sp. nov.
both absolutely (110–115 vs. 111–133 mm) and relative to the
length of head and body (70–88% vs. 87–103%; Fig. 25A).
Both species have dark hairs present over much of the dorsal
surface of the hind foot, but the ventral surface in A.
brownorum is much less heavily pigmented than that of A.
banahao, and is slightly broader (Fig. 10C,H).
The skull of A. brownorum is similar to that of A. banahao
sp. nov. but is smaller overall. The braincase is slightly more
elongate and globose (vs. somewhat more rectangular), the
rostrum is relatively more elongate and gracile, the incisive
foramina are less broad, the zygomatic plate is narrower and
the orbitotemporal fossa length is usually less (Fig. 25B), and
a plot of breadth of M1 vs. labial breadth of palate at M1
shows almost no overlap (Fig. 25C); this combination of
mensural characters separates all individuals. The palate of A.
banahao sp. nov. is more heavily pitted and fenestrated. These
species share the ‘‘abrae pattern’’ of carotid circulation,
lacking a stapedial foramen in the bullae (Fig. 5A). The
interparietals are similar in shape. The mandible of A. banahao
sp. nov. is similar to that of A. brownorum, but the coronoid
process is shorter, thinner, and directed more posteriorly, and
processes is shallower.
A PCA of 18 craniodental measurements showed substantial differences between these two species (Fig. 26; Table 8).
The first component, which accounted for 49% of the total
variance, loaded strongly on all measurements, indicating that
it is an indicator of size and robustness. The second
component, which accounted for 11% of the total variance,
was strongly dominated by high loadings on rostral and
diastema length (Table 8). Subsequent components had
eigenvalues of less than 2.0. Individuals of A. brownorum
had low scores on the first component, whereas most A.
banahao sp. nov. had higher scores, reflecting the generally
greater size and robustness of the latter species. Overlap was
great on the second component, although some A. brownorum
scored low on the component, indicating their proportionately
27
FIG. 20. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys sacobianus (USNM
304352, holotype); scale bar 5 5 mm.
long rostrum and diastema. Given the strong and consistent
morphological and genetic differences that distinguish these
species, we consider them to be distinct species.
Apomys brownorum differs in many respects from A.
zambalensis sp. nov., which occurs on the same mountain
(Mt. Tapulao) at lower elevations. Externally, there is little
overlap in head and body length and no overlap in a plot of
length of tail and hind foot (Fig. 27A), and most individuals of
A. zambalensis sp. nov. are heavier (Tables 3, 15). The pelage of
A. brownorum (Fig. 2B) is much darker dorsally and ventrally
than A. zambalensis sp. nov. (Fig. 2A), which is a rich orangebrown dorsally and has a very pale ochraceous wash ventrally.
The obvious morphological differences and genetic distance
between them mark these as clearly distinct species.
Apomys brownorum and A. zambalensis sp. nov. are easily
distinguished cranially, and there is no overlap in a plot of
PC1 and PC2 from the PCA of cranial measurements
(Fig. 6A). Apomys brownorum is consistently smaller in
virtually all measurements (Tables 3, 15); the skull of A.
brownorum is generally more slender, with a more globose
braincase and a more delicate rostrum (vs. squarish braincase
with a sturdy rostrum; Figs. 24, 46). The upper incisors are
narrower and also less deep, and the incisive foramina are
narrower. The palate is shorter and narrower, the molar
toothrow is shorter (Fig. 27B), the zygomatic plate is
narrower, and the lingual breadth at M3 is usually less
(Fig. 27C). Apomys brownorum lacks a stapedial foramen in
the bullae (Fig. 5A); the foramen is present in A. zambalensis
sp. nov. (Fig. 5B). The interparietal bone of A. brownorum is
28
of moderate anteroposterior width; that of A. zambalensis sp.
nov. is much wider. The mandible of A. zambalensis sp. nov. is
longer and more robust overall, with a shorter, wider, more
posteriorly inclined coronoid process and a broader, longer
angular process. All individuals are easily distinguished by this
combination of characters.
DISTRIBUTION—Apomys brownorum is currently known only
from mossy forest at a single locality near the peak of Mt.
Tapulao at ca. 2024 m elevation (Figs. 3, 14). No specimens
were taken at 1690 m in 391 trap-nights that yielded 50 captures
of A. zambalensis sp. nov. or at lower elevations where A.
zambalensis sp. nov. were equally common. We have no data
from 1690 to 2024 m, so we can infer only that the lower
elevational limit for the species falls somewhere within this
range, perhaps at ca. 1800 m, where there is a transition from
montane to mossy forest (Balete et al., 2009). Similar habitat
might occur on the other high peaks of the Zambales
Mountains, and this species should be sought there, especially
above about 1800 m. The Zambales Mountains are isolated
from other highland areas by a broad lowland plain; the Central
Cordillera, which has two species of Megapomys (A. abrae and
A. datae), is the nearest mountain range, so we doubt that A.
brownorum occurs outside of the Zambales Mountains.
Apomys (Megapomys) banahao sp. nov.
HOLOTYPE—FMNH 178501, adult male collected on 09 May
2004 by Eric A. Rickart, field number EAR 5279. A sample of
FIG. 21. Bivariate plots of measurements comparing Apomys abrae, A. datae, and A. sacobianus. (A) Length of tail vertebrae (TV) and length
of hind foot (HF). (B) Braincase height (BH) and rostral depth (RD). (C) Lingual breadth of palate at M3 (LBM3) and diastema length (DL).
muscle tissue was removed from the thigh in the field and
preserved in ethanol before preserving the specimen in
formaldehyde. In the museum, the skull was removed and
cleaned (see Methods). All parts are in good condition. This
specimen will be permanently deposited at the NMP. Measurements are in Table 9.
TYPE LOCALITY—Philippines: Luzon Island: Quezon Province: Mt. Banahaw: Barangay Lalo, 1465 m; 14.06635uN,
121.50855uE (from GPS).
PARATYPES (n 5 137)—Luzon Island: Quezon Prov.:
Tayabas Munic.: Brgy. Lalo: Mt. Banahaw, 1465 m (FMNH
178358, 178359, 178397, 178430–178510, 179450–179494,
179496–178500, 179502, 179507, 179508); Tayabas Munic.:
Brgy. Lalo: Mt. Banahaw, 1750 m (FMNH 178511–178544,
179503–179506, 179509–179517).
ETYMOLOGY—From the traditional Tagalog spelling of the
name of the mountain (Banahao) where this species occurs,
used as a noun in apposition.
DIAGNOSIS AND DESCRIPTION—A small species of the
subgenus Megapomys (HBL 125–146 mm, BOL 33.10–
35.25 mm) with a fairly short tail (86–103% of HBL). The
dorsal pelage is soft, dense, and moderately long; it is dark
brown, slightly paler laterally, with slight rusty tints (Fig. 1D).
The ventral pelage is dark gray at the base and white washed
with pale ashy-gray at the tips. The transition between the
dorsal and ventral pelage is usually fairly abrupt. The ears are
darkly pigmented. Dark brown fur covers the lower forelimb
and about half of the posterior portion of the forepaws and is
present as a dark brown area of variable size on about the
center of the dorsal surface of the hind foot, with white fur
both anterior and posterior. The hind feet are pigmented
ventrally (Fig. 10C). The tail is sharply bicolored, with the
dorsal surface dark grayish-brown and the ventral surface
nearly white.
The cranium of A. banahao (Fig. 28; Table 9) is small, with
a moderately long, slender rostrum. The zygomatic plate is
wide (2.94–3.52 mm) relative to the length of the cranium. The
incisive foramina are short (4.7–5.5 mm) and moderate in
width. The maxillary molariform toothrow is moderately
short (6.5–7.1 mm), and the toothrow is of moderate width, as
shown by the width of M1 (1.77–2.05 mm). The posterior
portion of the palate is more extensively pitted and perforated
than any species except A. magnus sp. nov., which is similar in
this character. There is no perforation of the bulla for a
stapedial artery (the ‘‘abrae pattern’’; Fig. 5A). The mandible
(Fig. 28C) is relatively small and slender, with a short, sharply
pointed coronoid process, sturdy angular process, and shallow
posterior margin between the condylar and angular processes.
The karyotype of A. banahao, based on three males from
Mt. Banahaw (FMNH 178481, 178482, 178524), is 2n 5 48, FN
$ 54 (Fig. 8D). The autosomal complement includes two pairs
of small metacentric or submetacentric chromosomes and 21
pairs of telocentric or subtelocentric chromosomes. The X
chromosome is large and submetacentric, and the Y is very
small and acrocentric.
COMPARISONS—Apomys banahao (Fig. 1D) is easily distinguished from A. datae (Fig. 1B). It is smaller in nearly all
measurements (Tables 2, 9), but with some overlap. Its dorsal
pelage is softer and denser and is slightly darker and less rustyred in tone. The ears of A. banahao are more darkly
pigmented. The ventral pelage is paler, and there are fewer
dark hairs on the dorsal surface of the hind feet. The rostrum
is shorter and less robust, the braincase is more globose and
less squarish, the interorbital breadth is less, the palate is
narrower, and the bullae lack a foramen for the stapedial
artery (‘‘abrae type’’; Fig. 5A), which is conspicuous in A.
datae (Fig. 5B). The interparietals are similar in shape. The
mandible of A. datae is much larger and proportionately more
robust, with a longer, wider coronoid process and broader,
longer angular process.
Apomys banahao is equally easily distinguished from A.
magnus sp. nov., with which it occurs syntopically at middle
elevations on Mt. Banahaw. It is smaller on average in
virtually all measurements, although with some overlap
(Tables 9, 12). A comparison of length of head and body
and length of tail distinguishes most individuals (Fig. 29A). Its
dorsal pelage is longer and softer (Fig. 1D) and is less rusty
than A. magnus sp. nov. (Fig. 1E), and it lacks the
conspicuous black tips on the dorsal guard hairs of A. magnus
sp. nov. Its fore- and hind feet have black hairs on the dorsal
surface, whereas those of A. magnus are nearly entirely white.
The ventral pelage of A. banahao is dark gray at the base, with
pale gray tips; that of A. magnus sp. nov. is pale gray at the
base with white tips. Its skull is much smaller and far more
gracile, usually with a narrower interorbital region (Fig. 29B).
The rostrum of A. banahao is shorter and less robust, and the
29
FIG. 22. Bivariate plots of measurements comparing Apomys sacobianus and A. zambalensis sp. nov. (A) Length of tail vertebrae (TV) and
length of hind foot (HF). (B) Diastema length (DL) and braincase height (BH). (C) Length of maxillary molariform toothrow (M1–M3) and
lingual breadth of palate at M3 (LBM3).
braincase is much less square (more globose) than that of A.
magnus sp. nov. The incisive foramina are less broad, and the
zygomatic plate is narrower. The maxillary toothrow is both
shorter and narrower, and the palate is narrower (Fig. 29C).
The bullae lack a foramen for the stapedial artery (the ‘‘abrae
pattern’’; Fig. 5A), which is conspicuous in A. magnus sp. nov.
(Fig. 5B). The interparietal bone of A. banahao is moderate in
anteroposterior width; that of A. magnus sp. nov. is much
wider. The mandible of A. magnus sp. nov. is larger and more
robust, with a less slender coronoid process and a broader
angular process. The combination of clear morphological and
genetic differences strongly supports the recognition of these
as distinct species.
Apomys banahao is generally similar to its sister-species, A.
brownorum, but differs in having pelage that is paler and
shorter, ventral fur that is washed with ashy gray (rather than
a pale ochraceous wash), a relatively shorter tail, a larger
cranium overall, a narrower M1 and palate, and usually
narrower zygomatic plate and foramina (for details, see
above). A PCA of craniodental measurements (Fig. 26;
Table 8) reflected these differences, as discussed above.
DISTRIBUTION—Apomys banahao is known from 1465 to
1750 m on Mt. Banahaw (Figs. 3, 14, 15) and probably occurs
from about 1400 m up to the peak at 2177 m. It should be sought
on the adjacent mountain, Mt. San Cristobal, which rises to
1470 m. Because Mts. Banahaw and San Cristobal are isolated
in a broad, low-elevation plain, we predict that this species will
not be found in any other area. If that is the case, then its
distribution is among the smallest of Megapomys species.
Apomys (Megapomys) minganensis sp. nov.
aurorae sp. nov., A. magnus sp. nov., A. sacobianus, and A.
zambalensis sp. nov. (see text and Table 7) based on specimens
included in Tables 3, 12, and 15. 1 5 A. zambalensis from Mt. Natib,
Bataan Province; 2 5 A. zambalensis from Mt. Tapulao, Zambales
Province; 3 5 A. magnus from Quezon Province; 4 5 A. aurorae from
Aurora Province; 5 5 A. sacobianus from Pampanga Province.
30
HOLOTYPE—FMNH 190949, adult male collected on 05 June
2006 by Mariano Roy M. Duya, field number MRMD 416. A
sample of muscle tissue was removed from the thigh in the
field and preserved in ethanol before preserving the specimen
in formaldehyde. In the museum, the skull was removed and
specimen will be permanently deposited at the NMP. Measurements appear in Table 9.
TYPE LOCALITY—Philippines: Luzon: Aurora Province:
Dingalan Munic.: 1.5 km S, 0.5 km W Mingan peak, 1681 m
elevation, 15.46802uN, 121.40039uE (GPS reading).
PARATYPES (n 5 97)—Luzon Island: Aurora Prov.: Dingalan Munic.: 1.7 km S, 1.3 km W Mingan Peak, 1540 m (FMNH
190941–190946, 190954, 190955); Dingalan Munic.: 1.8 km S,
1.0 km W Mingan Peak, 1677 m (FMNH 190774–190777,
190833–190845, 190847, 190848, 190936–190940); Dingalan
Munic.: 1.5 km S, 0.5 km W Mingan Peak, 1681 m (FMNH
190787–190793, 190867–190886, 190947, 190948, 190950–
190952, 190956–190960); Dingalan Munic.: 0.9 km S, 0.3 km
W Mingan Peak, 1785 m (FMNH 190778–190786, 190849–
190866, 191065).
ETYMOLOGY—An adjective based on the name of the
mountain range (Mingan Mountains) where this species
occurs.
analysis of log-transformed measurements of adult Apomys aurorae,
A. magnus, A. sacobianus, and A. zambalensis (see Fig. 23 and
Methods).
Principal component
Variable
1
0.894
0.570
Zygomatic breadth
0.837
Mastoid breadth
0.799
Nasal length
0.813
0.515
Rostral depth
0.721
Rostral length
0.756
0.735
0.727
0.753
Diastema length
0.651
Postpalatal length
0.573
Braincase height
0.564
0.482
Breadth of M1
0.624
0.086
Eigenvalue
8.109
45.05
2
3
4
0.309
20.427
20.073
20.188
0.156
0.123
0.289
0.102
20.214
20.237
20.420
0.531
0.615
0.155
20.144
20.743
0.072
20.431
2.179
12.116
0.116
20.271
20.102
20.020
0.004
20.013
0.057
20.302
0.107
0.330
0.038
20.291
0.301
20.479
20.144
0.270
0.409
20.380
1.124
6.25
0.126
20.245
20.017
20.043
0.025
0.449
0.098
0.115
0.185
20.054
20.143
0.091
0.031
20.453
20.283
0.043
20.117
0.657
1.101
6.12
DIAGNOSIS AND DESCRIPTION—A fairly small species of
Megapomys (HBL 128–145 mm, BOL 33.2–35.0 mm; Table 9), with a tail about 94% (range 87–101%) of HBL. The
dorsal pelage is dark brown with rusty-orange tips on the
hairs, lying over dark gray underfur (Fig. 2E). The ventral
pelage is dark gray at the base, with paler tips that usually
have an ochraceous wash. On live or fresh specimens, the eyes
are noticeably small. The tail is dark brown dorsally, always
with some dark hairs and pigment in the scales ventrally;
nearly all individuals have a small white tip, 1–4 mm long, on
the tail. The dorsal surface of the hind feet is dark brown, with
dark brown hairs reaching fully onto the toes; the ventral
surface is lightly to heavily pigmented, except the pads, which
are usually less darkly pigmented (Fig. 10F). The hallux is
long, reaching to or nearly to the top of the adjacent plantar
pad (Fig. 10F). The forefeet are almost entirely covered by
dark fur that extends down onto the foot from the forearm.
The pigmented area at the posterior tip of the scrotum of adult
males is very dark brown.
The skull of A. minganensis (Fig. 30) is of average overall size
in the subgenus Megapomys, with a BOL of 33.2–35.0 mm. In
general configuration, the skull is similar to those of A. aurorae
sp. nov. and A. sierrae sp. nov. in having a fairly globose
braincase, moderately gracile rostrum, broad incisive foramina,
lightly pitted palate, and the ‘‘datae pattern’’ of carotid
circulation (Fig. 5B). The rostrum of A. minganensis is
relatively short and narrow, and the orbitotemporal and
postpalatal regions are short. The maxillary toothrow of A.
minganensis is unusually short, the molars are narrow, and the
molar toothrows are nearly parallel. The interparietal is
variable in shape but usually is somewhat narrow in anteroposterior width. The mandible is short and slender, with a short
coronoid process and relatively narrow angular process.
COMPARISONS—Compared with the sympatric A. aurorae sp.
nov., A. minganensis differs externally in many respects.
Apomys minganensis has dark dorsal fur with rusty tips and
dark gray underfur (Fig. 2E), rather than rich rusty-brown fur
with medium gray underfur (Fig. 2F), and is darker ventrally,
having fur that is dark gray at the base (rather than medium to
pale gray), with tips with an ochraceous wash (rather than
white or nearly white with a pale ochraceous wash). The hind
feet of A. minganensis are covered by dark hairs dorsally,
whereas those of A. aurorae sp. nov. are usually white or have
scattered dark hairs that do not reach the base of the toes (i.e.,
the hair at the base of the toes is white). The hind feet of A.
minganensis are typically shorter and broader than those of A.
aurorae sp. nov., and the hallux of A. aurorae sp. nov. is
shorter, typically reaching only the base or the middle of the
adjacent plantar pad (Fig. 10G). The forefeet of A. minganensis have dark fur over the entire dorsal surface, but those of
A. aurorae sp. nov. are usually white, sometimes with dark
hairs over a central strip of the forefoot. The tail of A.
minganensis is always dark dorsally and usually has substantial
amounts of pigment and dark hair ventrally, whereas that of
A. aurorae sp. nov. is dark to medium brown dorsally and
either pure white or white with only some scattered dark hairs
and bits of dark pigment ventrally. Apomys minganensis nearly
always has a tiny white tip on the tail (over 95%), whereas A.
aurorae sp. nov. rarely has such a tip (less than 3%). The tail of
A. aurorae sp. nov. averages longer than that of A.
minganensis, and A. aurorae n. sp. also averages greater in
HBL, but there is considerable overlap in both of these
measurements (Fig. 31A).
The skull of A. minganensis is also easily distinguished from
that of A. aurorae sp. nov. There is no overlap in rostral depth,
orbital length, or length of the maxillary toothrow (Tables 9,
15; Fig. 31B,C); the M1 of A. minganensis is narrower; and
there is little overlap in lingual breadth of the palate at M3
(Fig. 31C) or in postpalatal length. Overall, the skull of A.
minganensis is slightly smaller and less elongate than that of A.
aurorae sp. nov. The carotid circulation pattern is the same in
these two species. The interparietal of A. minganensis is usually
narrower than that of A. aurorae sp. nov. The mandible of A.
aurorae sp. nov. is larger and more robust than that of A.
minganensis, with a longer and more slender coronoid process
and broader angular process.
Apomys minganensis is closely related to A. sierrae sp. nov.
and also occurs nearby. These two species are easily
distinguished. Apomys minganensis has longer, denser dorsal
fur that is dark brown rather than the rusty reddish-brown of
nearby populations of A. sierrae sp. nov. (Fig. 2E,C). The
ventral fur of A. minganensis is usually dark gray at the base
and pale gray with an ochraceous wash at the tips, whereas A.
sierrae sp. nov. has ventral fur that is medium to pale gray at
the base and either white or white washed with ochraceous at
the tips. The tail of A. minganensis is much darker dorsally,
always with scattered dark hairs and pigment ventrally; that of
A. sierrae sp. nov. is less dark dorsally and usually unpigmented
ventrally. Additionally, the tip (1–4 mm) of the tail is white
dorsally and ventrally in about 95% of A. minganensis, whereas
that of A. sierrae sp. nov. virtually always retains the usual
dorsal and ventral color. The dorsal surface of the hind foot of
A. minganensis is covered by dark hair, whereas that of A.
sierrae sp. nov. has only a few scattered dark hairs among the
predominantly white hair. The hallux of A. sierrae sp. nov. is
short, reaching only to about the base of the adjacent
interdigital plantar pad, whereas that of A. minganensis is
longer, reaching to the middle or top of the adjacent pad.
External measurements of these two species are generally
31
FIG. 24. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys brownorum sp. nov.
(FMNH 183524, holotype); scale bar 5 5 mm.
similar and overlapping (Tables 9, 11, 12), but A. sierrae sp.
nov. averages larger in most respects (e.g., ear and hind foot
length; Fig. 32A).
The skull of A. minganensis (Fig. 30) is similar to that of A.
sierrae sp. nov. (Fig. 34), but a number of unambiguous
differences are apparent, and there is no overlap in the PC1
and PC2 of cranial measurements in the PCA that includes all
Megapomys (Fig. 6A). Overall, the skull of A. minganensis is a
bit shorter and more compact than that of A. sierrae sp. nov.,
with a distinctly less robust rostrum (no overlap in rostral
depth), a shorter toothrow with narrower molars, and a palate
that is usually narrower (Fig. 32B,C). The maxillary toothrows of A. minganensis are nearly parallel, whereas those of A.
sierrae sp. nov. diverge posteriorly, and the palate of A. sierrae
sp. nov. is more heavily pitted and perforated. In A. sierrae sp.
nov., the foramen in the bulla for the stapedial artery is absent
(the ‘‘abrae pattern’’; Fig. 5A), whereas in A. minganensis, it is
always present (the ‘‘datae pattern’’; Fig 5B). The interparietal
FIG. 25. Bivariate plots of measurements comparing Apomys brownorum and A. banahao spp. nov. (A) Length of tail vertebrae (TV) and
length of head and body (HBL). (B) Zygomatic plate width (ZP) and orbitotemporal length (OL). (C) Labial palatal breadth at M1 (PBM1) and
breadth of M1 (BM1).
32
analysis of log-transformed measurements of adult Apomys banahao
and A. brownorum (see Fig. 26 and Methods).
Principal component
Variable
brownorum and A. banahao spp. nov. (see text and Table 8) based on
specimens in Tables 3 and 9.
of A. minganensis is usually anteroposteriorly narrower than
that of A. sierrae sp. nov. The mandibles are similar, but that
of A. minganensis is a bit more robust, with a more deeply
concave posterior margin between the condylar and angular
processes.
To further assess the distinctiveness of A. minganensis
relative to A. aurorae sp. nov. and A. sierrae sp. nov., we
conducted a PCA of 18 craniodental measurements of our
samples of all three species (Tables 9, 11, 12, 15). The first
component, which accounted for 40% of the total variance,
loaded strongly on nearly all measurements, with rostral
length, diastema length, and height of braincase loading least
strongly (Table 10). The second component, which accounted
for 15% of the variance, loaded most strongly (and positively)
on rostral and diastema length and (negatively) on length of
the molar toothrow and breadth of M1. PC3 and PC4 had
eigenvalues of less than 1.5. A plot of the first two components
(Fig. 33) showed A. minganensis falling outside of the polygon
1
0.897
0.740
Zygomatic breadth
0.901
Mastoid breadth
0.668
Nasal length
0.635
0.313
Rostral depth
0.906
Rostral length
0.434
0.761
0.634
0.880
Diastema length
0.445
Postpalatal length
0.845
3
0.615
Braincase height
0.463
0.679
Breadth of M1
0.649
0.804
Eigenvalue
8.904
49.47
2
3
4
20.334
0.434
0.179
0.274
20.433
0.073
0.114
20.699
0.080
20.149
0.278
20.638
20.344
20.030
0.292
0.399
20.035
0.106
1.991
11.06
20.036
0.282
0.164
0.447
20.029
20.659
0.162
0.065
20.155
20.423
20.217
0.255
20.088
0.229
0.517
20.480
0.195
20.267
1.754
9.75
20.004
0.090
0.104
20.281
20.303
20.019
0.059
20.187
20.331
20.221
0.171
0.278
0.013
0.613
20.414
20.001
0.046
0.186
1.077
5.99
of A. sierrae sp. nov. and far from that of A. aurorae sp. nov.
Individuals of A. minganensis scored low on PC1, reflecting its
small size relative to the other two species, although there was
slight overlap at the margins of the polygons. On PC2, A.
minganensis scored high, reflecting its long rostrum and
diastema and short molar toothrow and narrow M1. Apomys
aurorae sp. nov. scored low on PC2, reflecting its typically
shorter rostrum and diastema and longer molar toothrow and
wider M1, although these two species showed some overlap on
this component. Individuals of A. sierrae sp. nov. varied
greatly on PC2, overlapping extensively with A. minganensis,
but most individuals scored lower than those of A. minganensis. We conclude that A. minganensis differs consistently
from these two closely related species. Additional comparisons
between A. aurorae sp. nov. and A. sierrae sp. nov., which
overlap extensively on these two components, are made below.
DISTRIBUTION—We captured A. minganensis along our
transect on the Mingan Mountains from 1540 to 1785 m
FIG. 27. Bivariate plots of measurements comparing Apomys brownorum and A. zambalensis spp. nov. (A) Length of tail vertebrae (TV) and
length of hind foot (HF). (B) Length of maxillary molariform toothrow (M1–M3) and labial palatal breadth at M1 (PBM1). (C) Zygomatic plate
width (ZP) and lingual breadth of palate at M3 (LBM3).
33
TABLE 9. Cranial and external measurements (mean 6 1 S.D. and range) of Apomys banahao, A. minganensis, and A. sierrae (part).
Measurement
Zygomatic breadth
Mastoid breadth
Nasal length
Incisive foramen
length
Rostral depth
Rostral length
Maxillary toothrow
length
Labial palatal breadth
at M1
Diastema length
Postpalatal length
Lingual palatal
breadth at M3
Braincase height
Breadth of M1
Breadth of incisors at
tip
Width of zygomatic
plate
Length of head and
body
Total length
Length of tail
vertebrae
Length of hind foot
Length of ear
Weight (g)
Apomys banahao
Apomys minganensis
Mt. Banahaw, 1465–1750 m, Quezon Prov.
Mingan Mtns., 1540–1785 m, Aurora Prov.
M-holotype
178501
M (n = 13)
34.23
—
5.96
—
17.96
—
14.26
—
14.16
—
5.32
—
7.45
—
14.96
—
12.03
—
6.81
—
7.35
—
9.00
—
12.11
—
4.87
—
11.21
—
1.84
—
2.07
—
3.31
—
137
—
266
—
129
—
37
—
23
—
80
—
34.43 6 0.61 (12)
33.34–35.39
5.98 6 0.28 (12)
5.47–6.33
18.21 6 0.47 (12)
17.36–18.99
14.29 6 0.41 (12)
13.71–15.09
13.96 6 0.47 (12)
13.06–14.64
5.20 6 0.23 (12)
4.84–5.53
7.46 6 0.22 (12)
7.10–7.75
14.96 6 0.45 (12)
14.17–15.70
11.99 6 0.27 (12)
11.56–12.38
6.83 6 0.21
6.47–7.19
7.38 6 0.19 (12)
7.03–7.70
9.33 6 0.31 (12)
8.95–9.86
11.88 6 0.34 (12)
11.25–12.53
4.96 6 0.22 (12)
4.51–5.30
10.80 6 0.39 (12)
10.02–11.44
1.91 6 0.07
1.77–2.05
2.14 6 0.12 (12)
1.95–2.34
3.25 6 0.19 (12)
2.94–3.52
137.9 6 7.5 (11)
125–154
265.8 6 10.4 (11)
250–287
127.9 6 4.8 (11)
118–133
36.5 6 0.8 (11)
35–37
23.2 6 0.6 (12)
22–24
78.8 6 5.9 (12)
71–92
FMNH
F (n = 11)
34.13 6 0.74
33.10–35.25
5.88 6 0.18
5.58–6.15
18.22 6 0.38
17.69–18.91
14.25 6 0.28
13.71–14.55
13.99 6 0.40
13.40–14.81
5.14 6 0.27
4.72–5.51
7.47 6 0.20
7.23–7.87
15.11 6 0.36
14.64–15.85
11.88 6 0.41
11.13–12.35
6.78 6 0.19
6.52–7.09
7.43 6 0.12
7.18–7.60
9.35 6 0.36
8.81–9.89
11.80 6 0.29
11.38–12.18
5.07 6 0.22
4.69–5.44
10.88 6 0.26
10.55–11.35
1.87 6 0.06
1.78–1.98
2.26 6 0.11
2.09–2.42
3.08 6 0.13
2.94–3.35
137.3 6 4.9 (10)
128–143
261.6 6 8.0 (10)
250–271
124.3 6 5.9 (10)
111–130
35.7 6 1.2 (10)
33–37
23.3 6 0.7 (10)
22–24
80.1 6 4.3 (10)
72–86
(Figs. 3, 14, 15; Balete et al., this volume), and we suspect that
it occurs up to the top of the peak at 1910 m. At our two upper
sampling areas (1681 and 1785 m), it was the only species of
Megapomys present. At 1677 m, one of 25 specimens was an
A. aurorae sp. nov., and at 1540 m one of nine Megapomys
was A. aurorae sp. nov. At 1305, 1074, 902, and 733 m, only A.
aurorae sp. nov. were captured. We suspect that A. minganensis is widespread in the Mingan Mountains above about
1500 m. Our surveys to the north of the Mingan Mountains, in
the southern portions of the central Sierra Madre, yielded only
specimens of A. sierrae sp. nov., and so we consider it unlikely
that A. minganensis occurs there. No information on small
mammals is currently available from the Dingalan Mountains,
just to the south of the Mingan Mountains, or from the peaks
34
M-holotype
190949
FMNH
34.82
—
6.38
—
18.03
—
14.47
—
14.02
—
5.04
—
6.78
—
15.72
—
11.29
—
6.64
—
7.43
—
9.80
—
11.87
—
4.90
—
10.53
—
1.82
—
1.98
—
3.57
—
145
—
278
—
133
—
34
—
18
—
92
—
M (n = 9)
34.06 6 0.47
33.42–34.82
6.10 6 0.13
5.97–6.38
17.19 6 0.48
16.44–18.03
14.20 6 0.15 (8)
14.02–14.47
14.15 6 0.28
13.78–14.70
5.12 6 0.12
4.92–5.30
6.63 6 0.13
6.40–6.78
15.37 6 0.29
15.03–15.72
11.07 6 0.17
10.92–11.37
6.63 6 0.16
6.45–6.94
7.19 6 0.18
6.90–7.43
9.57 6 0.14
9.42–9.82
11.24 6 0.34
10.88–11.87
4.86 6 0.08
4.73–4.93
10.69 6 0.21
10.38–10.96
1.80 6 0.06
1.70–1.87
1.97 6 0.05
1.91–2.05
3.35 6 0.15
3.15–3.57
138.2 6 4.4
132–145
269.2 6 6.3
260–279
131.0 6 3.6
126–138
33.2 6 1.1
31–34
18.2 6 0.4
18–19
76.9 6 7.8
66–92
F (n = 10)
34.02 6 0.55
33.16–34.97
6.06 6 0.13
5.80–6.23
17.12 6 0.23
16.81–17.62
14.04 6 0.18
13.77–14.29
14.02 6 0.40
13.55–14.71
5.01 6 0.18
4.60–5.23
6.71 6 0.14
6.43–6.86
15.28 6 0.35
14.73–15.86
10.87 6 0.30
10.39–11.34
6.67 6 0.14
6.48–6.95
7.28 6 0.17
7.05–7.55
9.59 6 0.21
9.38–9.97
11.15 6 0.24
10.81–11.50
4.89 6 0.16
4.68–5.22
10.53 6 0.18
10.13–10.82
1.81 6 0.04
1.74–1.87
1.99 6 0.08
1.85–2.10
3.40 6 0.17
3.09–3.67
135.3 6 5.0 (9)
128–141
260.7 6 9.1
246–275
125.2 6 5.9 (9)
116–134
33.4 6 0.8
32–35
18.2 6 0.4
18–19
73.7 6 7.0
66–86
of the southern Sierra Madre range in Rizal and adjacent
Quezon provinces; surveys there would be valuable to
determine whether this species is present, or whether yet more
unknown species are present. If this species is indeed confined
to the high elevations of the Mingan Mountains, it has one of
the smaller ranges among species of Apomys.
Apomys (Megapomys) sierrae sp. nov.
2005 by Mariano Roy M. Duya, field number MRMD 354B.
TABLE 9.
Extended.
Apomys sierrae
Mt. Cetaceo, 1300–1400 m, Cagayan Prov.
M-holotype
FMNH 185884
35.40
—
6.22
—
17.89
—
14.22
—
14.29
—
5.60
—
7.75
—
15.52
—
11.91
—
7.30
—
7.68
—
9.60
—
11.92
—
5.62
—
10.66
—
1.90
—
2.28
—
3.68
—
131
—
271
—
140
—
37
—
19
—
90
—
Mt. Cetaceo, 1500–1550 m, Cagayan Prov.
M (n = 8)
35.15 6 0.46
34.32–35.86
6.09 6 0.13
5.90–6.25
18.10 6 0.48
17.32–18.99
14.20 6 0.27
13.78–14.75
14.05 6 0.35
13.45–14.61
5.29 6 0.45
4.55–5.79
7.49 6 0.16
7.26–7.75
14.95 6 0.48
14.21–15.52
12.05 6 0.20
11.84–12.38
7.66 6 0.26
7.24–7.93
7.85 6 0.29
7.62–8.45
9.16 6 0.36
8.61–9.60
11.63 6 0.29
11.07–11.92
5.47 6 0.21
5.17–5.81
10.63 6 0.16 (7)
10.38–10.78
1.93 6 0.09
1.82–2.04
2.16 6 0.10 (7)
1.98–2.28
3.58 6 0.26
3.34–4.19
133.4 6 6.4
124–144
267.1 6 6.2
254–273
133.8 6 4.4
129–140
35.5 6 1.0
34–37
19.0 6 0.9
18–21
84.5 6 5.9
73–92
F (n = 4)
35.24 6 0.46
34.69–35.64
6.06 6 0.33
5.58–6.29
18.24 6 0.78
17.39–18.95
14.29 6 0.19
14.03–14.45
13.88 6 0.39
13.36–14.25
5.33 6 0.52
4.86–5.99
7.48 6 0.21
7.19–7.69
14.86 6 0.35
14.40–15.19
11.89 6 0.16
11.66–12.03
7.55 6 0.17
7.38–7.70
7.87 6 0.17
7.77–8.12
9.10 6 0.31
8.81–9.48
11.60 6 0.18
11.46–11.86
5.46 6 0.10
5.35–5.55
10.72 6 0.17
10.51–10.91
1.89 6 0.09
1.80–1.97
2.11 6 0.08
2.04–2.22
3.67 6 0.12
3.50–3.77
140.8 6 6.8
134–148
276.3 6 4.6
271–282
135.5 6 5.0
129–141
35.1 6 0.9
34–36
19.6 6 1.0
18–20
81.5 6 6.6
74–88
TYPE LOCALITY—Philippines: Luzon: Cagayan Province:
3.5 km SW Mt. Cetaceo peak, 1400 m elevation, 17.69561uN,
122.01683uE.
PARATYPES (n 5 408)—Luzon Island: Cagayan Prov.: 1.5 km
SW Mt. Cetaceo peak, 1550 m (FMNH 185834–185841, 185861–
185880, 185900, 185946, 185961); 2.0 km SW Mt. Cetaceo
peak, 1500 m (FMNH 185805, 185815–185833, 185842–185845,
185854–185860, 185896–185898, 185904, 185905, 185938–
185945, 185955–185960); 3.5 km SW Mt. Cetaceo peak,
1400 m (FMNH 185803–185814, 185846–185853, 185881,
185883, 185885–185895, 185899, 185901–185903, 185906,
M (n = 12)
35.31 6 0.57
34.68–36.43
6.44 6 0.22
6.15–6.77
18.29 6 0.48
17.60–19.39
14.61 6 0.28
14.21–15.21
14.21 6 0.59 (11)
13.49–15.55
5.28 6 0.22
5.00–5.71
7.63 6 0.21 (11)
7.23–7.84
15.12 6 0.55
14.40–16.25
12.02 6 0.24
11.46–12.30
7.39 6 0.19
7.11–7.70
7.82 6 0.39
7.19–8.44
9.52 6 0.30
9.02–10.00
11.77 6 0.28
11.21–12.10
5.44 6 0.26
4.87–5.66
10.90 6 0.31
10.41–11.40
1.91 6 0.07
1.83–2.02
2.28 6 0.09
2.14–2.40
3.56 6 0.21
3.29–3.85
143.3 6 8.7 (10)
132–163
274.4 6 12.5 (10)
260–295
131.6 6 6.7 (11)
124–148
36.7 6 1.2
35–39
20.2 6 0.6
19–21
84.9 6 9.5 (11)
75–110
F (n = 10)
35.30 6 0.50
34.70–36.25
6.30 6 0.17
5.95–6.46
18.21 6 0.39
17.58–18.76
14.38 6 0.34
13.68–14.76
14.15 6 0.21
13.80–14.50
5.57 6 0.16
5.28–5.77
7.51 6 0.19
7.28–7.78
15.05 6 0.43
14.59–15.75
12.13 6 0.34
11.73–12.60
7.47 6 0.23
7.24–7.91
7.77 6 0.27
7.25–8.05
9.56 6 0.29
9.03–10.04
11.76 6 0.31
11.24–12.26
5.42 6 0.22
5.10–5.84
10.80 6 0.41
9.85–11.30
1.89 6 0.08
1.73–2.03
2.30 6 0.12
2.06–2.53
3.48 6 0.25
3.07–3.87
140.6 6 4.2 (9)
135–146
272.1 6 7.9 (9)
260–281
131.6 6 6.4 (9)
118–137
35.7 6 1.0 (9)
34–37
19.7 6 0.7 (9)
18–20
77.2 6 4.6 (9)
72–85
185936, 185937, 185947–185954, 185962–185970); Baggao
Munic.: Barrio Via, Sitio Hot Springs, W Foothills Sierra
Madre Mtns., 760–800 m (USNM 574889); Callao Munic.: Mt.
Cetaceo, 1450 m (FMNH 147166–147169); Gonzaga Munic.:
Brgy. Magrafil: Sitio Masok: Mt. Cagua, 800 m (FMNH
176562–176576); Penablanca Munic.: Brgy. Lapi: Sitio Baua:
Mt. Cetaceo, 1300 m (FMNH 180298–180364); Penablanca
Munic.: Brgy. Mangga: Sitio Lowak: Mt. Cetaceo, 1100 m
(FMNH 176552–176558).
Isabela Prov.: Los Dos Cuernos, E of Tuguegarao (FMNH
142060); Mt. Dipalayag, E of San Mariano (FMNH 142061,
142062).
Nueva Vizcaya Prov.: Quezon Munic.: 0.8 km N, 0.55 km E
Mt. Palali peak, 1420 m (FMNH 186726–186760, 186778,
186786, 186820–186825,194934–194947); Quezon Munic.:
35
FIG. 28. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys banahao sp. nov. (FMNH
1.75 km N, 0.1 km E Mt. Palali peak, 1300 m (FMNH 194948–
194961); Quezon Munic.: 2.75 km N, 0.3 km W Mt. Palali
peak, 1040 m (FMNH 194962–194977); Quezon Munic.: 3.05 km
N, 0.1 km E Mt. Palali peak, 900 m (FMNH 194978–194998);
Quezon Munic.: 3.35 km N, 0.5 km W Mt. Palali peak, 780 m
(FMNH 194999–195015); Quezon Munic.: Mt. Palali peak,
1700 m (FMNH 186761–186777, 186779–186785, 186826,
186827, 194923–194933).
Quirino Prov.: Nagtipunan Munic.: Brgy. Disimungal: Sitio
Km 18: Mt. Lataan, 1200 m (FMNH 176559–176561);
Nagtipunan Munic.: Brgy. Matmad: Sitio Mangitagud:
Mungiao Mtns., 450 m (FMNH 180365–180373).
Palaui Island: Cagayan Prov.: Sta. Ana Munic.: Brgy. San
Vicente: 4.25 km S of Cape Engano Lighthouse, 153 m (FMNH
191232–191237).
ETYMOLOGY—From the name of the mountain range (Sierra
Madre) where most of the specimens of this species originated,
used as a noun in the genitive case.
DIAGNOSIS AND DESCRIPTION—A species of the subgenus
Megapomys of average size (HBL 124–171 mm, averaging
FIG. 29. Bivariate plots of measurements comparing Apomys banahao and A. magnus spp. nov. (A) Head and body length (HBL) and length
of tail vertebrae (TV). (B) Basioccipital length (BOL) and interorbital breadth (IB). (C) Length of maxillary molariform toothrow (M1–M3) and
labial palatal breadth at M1 (PBM1).
36
FIG. 30. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys minganensis sp. nov.
133–150 mm; weight 73–111 g, averaging 79–88 g), with a tail
that is about equal to the HBL (85–111%, averaging 95–
102%). In the Sierra Madre range, the dorsal pelage is dark
brown with conspicuous rusty-reddish tints (Fig. 2C); on Mt.
Palali in the Caraballo Mountains, the dorsal pelage is a
medium brown with yellow tint, and the skin of the ears and
feet are paler than in individuals from the Sierra Madre
(Fig. 2D). The ventral pelage is medium to pale gray at the
base and white or white washed with pale ochraceous at the
tips. The tail is sharply bicolored, dark brown dorsally
(somewhat paler on individuals from Mt. Palali) and usually
white (unpigmented) ventrally. As with most species of
Apomys, a few individuals (less than 5%) have a white tip on
the tail. The dorsal surface of the hind foot of A. sierrae is
mostly white, with only a few scattered dark hairs. The ventral
surface is moderately to darkly pigmented (darker on those
FIG. 31. Bivariate plots of measurements comparing Apomys minganensis and A. aurorae spp. nov. (A) Length of tail vertebrae (TV) and
length of head and body (HBL). (B) Rostral depth (RD) and orbitotemporal length (OL). (C) Length of maxillary molariform toothrow (M1–
3
M ) and lingual breadth of palate at M3 (LBM3).
37
FIG. 32. Bivariate plots of measurements comparing Apomys minganensis and A. sierrae spp. nov. (A) Length of ear (EAR) and length of
hind foot (HF). (B) Rostral depth (RD) and rostral length (RL). (C) Length of the maxillary toothrow (M1–M3) and labial palatal breadth at
1
M (PBM1).
from the Sierra Madre than from Mt. Palali), with relatively
small plantar pads, and the hallux is short, usually extending
only to about the base of the adjacent interdigital plantar pad
(Fig. 10E).
The skull of A. sierrae (Fig. 34) is of average size within
Megapomys (BOL 33.5–37.5 mm, with individual populations
averaging 35.1–36.1 mm; Tables 9, 11, 12). It is most similar
overall to several of the species to which it is most closely
related: A. aurorae sp. nov., A. minganensis, and A.
zambalensis sp. nov. (Apomys magnus sp. nov. is much larger
and differs in other respects.) The rostrum is rather long and
slender, and the braincase is globose and slightly elongated.
The maxillary molar teeth are rather narrow, and the
toothrows diverge posteriorly. The palate is unusually heavily
perforated and pitted, and the postpalatal region is of average
length. The foramen for the stapedial artery in the bulla is
absent (the ‘‘abrae pattern’’; Fig. 5A). The interparietal is
aurorae, A. minganensis, and A. sierrae spp. nov. (see text and
Table 10) based on specimens in Tables 9, 11, 12, and 15.
38
usually anteroposteriorly wide. The mandible (Fig. 34C) is
rather slender. The coronoid process is relatively erect (less
posteriorly directed) and sharply pointed, the angular process
is relatively narrow, and the posterior margin between the
condylar and angular processes is deeply concave.
As noted above, our samples from Cagayan, Quirino, and
Nueva Vizcaya provinces show no geographic pattern of
genetic relatedness, even though they come from distant
mountains and from Palaui Island (Figs. 3, 7, 35). Our sample
from Palaui Island showed slight genetic differentiation
(Fig. 7), and cranial measurements are slightly smaller than
those on the nearby mainland (Tables 9, 11, 12), but the latter
is explained in part by the fact that all three Palaui Island
specimens were young animals with partially open cranial
sutures and had not completed growth. Specimens from
Nueva Vizcaya have paler fur than those from Cagayan and
Quirino but are otherwise externally indistinguishable. Comparison of measurements (Tables 9, 11, 12) shows extensive
overlap of individuals from all of our samples, and we have
noted no discrete cranial differences among them.
To further investigate possible divergence within the set of
populations here referred to A. sierrae, we conducted a PCA
of 18 craniodental measurements of the individuals included in
Tables 9, 11, and 12. In this analysis, we broke our samples
not only into those from each geographic locality, but also
designated them by groups on the basis of elevation along the
Mt. Cetaceo and Mt. Palali transects because often two
species of Megapomys are present at different elevations on
Luzon mountains (see Discussion). The first PC, which
accounted for 34% of the total variance, loaded heavily on
all measurements except length of upper molar toothrow,
breadth of M1, and height of braincase (Table 13), thus
generally indicating size and robustness. The second component, which accounted for 14% of the variance, loaded heavily
on length of upper molar toothrow, palatal breadth at M1,
and breadth of M1; diastema length and postpalatal length
loaded negatively. Subsequent components had eigenvalues of
less than 1.5.
Inspection of the scores of individuals on the first two
components (Fig. 36) shows nearly complete overlap on the
first component, with six individuals from Mt. Palali scoring
outside of the primary range of values (i.e., scoring higher than
1.5 on PC1). These individuals (FMNH 186777, 194926, 194970,
analysis of log-transformed measurements of adult Apomys aurorae,
A. minganensis, and A. sierrae (see Fig. 33 and Methods).
Principal component
Variable
1
0.828
0.427
Zygomatic breadth
0.836
Mastoid breadth
0.619
Nasal length
0.487
0.566
Rostral depth
0.854
Rostral length
0.330
0.823
0.692
0.829
Diastema length
0.245
Postpalatal length
0.592
3
0.753
Braincase height
0.321
0.520
Breadth of M1
0.676
0.439
Eigenvalue
7.191
39.95
2
3
4
0.332
0.490
20.005
0.245
0.459
0.019
20.165
0.698
20.156
20.576
20.276
0.758
0.386
20.222
0.035
20.529
20.160
20.172
2.679
14.88
20.092
20.325
0.050
0.041
0.343
0.192
0.049
0.334
20.131
20.071
0.266
0.073
20.303
0.153
20.666
0.229
20.320
0.031
1.200
6.67
0.261
20.276
20.130
20.333
20.242
0.228
0.072
20.180
0.239
0.036
20.203
0.224
0.344
0.008
20.477
20.291
0.110
0.262
1.081
6.01
195007, 195014, 195015) have unusually heavily worn teeth
and skulls that are more robust than usual; they appear simply
to be ‘‘old adults’’ that are otherwise not distinguishable from
other individuals from Mt. Palali. On PC2, individuals from
Palaui Island, two from Mt. Cagua (which is the sample on
mainland Luzon nearest to Palaui Island; Figs. 3, 35) and four
from Mt. Cetaceo, score near one another, outside of the
primary range of values (i.e., they have scores lower than
21.5). As noted above, the three from Palaui Island are young
adults that have not fully completed growth; the same is true
for the two from Cagua and four from Cetaceo that have low
scores. The differences in measurements are largely those
associated with unworn teeth. We note no differences in the
crania that are not associated with their young age.
Aside from variation associated with these outliers, which
we ascribe to age-related differences, all individuals assigned
here to A. sierrae fall in a tight area of overlap in the plot of
PC1 vs. PC2, and we conclude that craniodental morphometric variation is slight. Because the extent of geographic
variation in cyt b also is slight, we hypothesize that all of
these populations represent a single, widespread species.
COMPARISONS—Apomys sierrae is easily distinguished from its
close relative A. minganensis, as described in detail above
(Fig. 32); A. minganensis has longer, denser, and darker dorsal
fur and many dark hairs on the dorsal surface of the hind foot,
and the hallux is long, reaching nearly to the top of the adjacent
plantar pad, rather than reaching only to the bottom of the pad
as in A. sierrae. The skull has a shorter toothrow with narrower
molars and a foramen in the bulla for the stapedial artery that is
relatively large and conspicuous, rather than absent (Fig. 5). A
PCA of craniodental measurements comparing A. sierrae with
A. minganensis also showed discrete differences (Fig. 33;
Table 10; see A. minganensis account, above).
Apomys sierrae differs from A. magnus sp. nov., to which it
is closely related, by usually being smaller (e.g., HBL
averaging 133–150 mm vs. 145–148 mm, BOL 35.1–36.1 mm
vs. 37.0–37.7 mm). The dorsal pelage of A. sierrae (Fig. 2C,D)
is dark brown with rusty reddish tones or a rich rusty orangebrown, whereas that of A. magnus (Fig. 1E) is dark brown
with prominent black guard hairs and virtually no reddish
tones. Ventrally, A. sierrae has fur that is dark gray at the base
and pale gray at the tip with an ochraceous wash, whereas that
of A. magnus sp. nov. is somewhat paler gray at the base and
nearly white at the tip. The ventral surface of the hind foot is
usually darkly pigmented in both species, but the hallux of A.
magnus sp. nov. is longer, reaching nearly to the top of the
adjacent plantar pad, rather than only to its base
(Fig. 10D,E). A comparison of hind foot length against
weight for the two species shows little overlap (Fig. 37A).
The crania of A. sierrae and A. magnus sp. nov. differ
conspicuously. That of A. magnus is generally larger and more
robust, with little overlap in basioccipital length, interorbital
breadth, zygomatic breadth, mastoid breadth, nasal length,
length of the incisive foramina, length of the maxillary
toothrows, and palatal breadth. Plots of orbital length against
postpalatal length, and of rostral length against depth, show
good but not complete separation among nearly all individuals
(Fig. 37B,C); additionally, the stapedial foramen in the bulla
is large and conspicuous in A. magnus (the ‘‘datae pattern’’;
Fig. 5B) but absent in A. sierrae (the ‘‘abrae pattern’’;
Fig. 5A), allowing easy identification of skulls.
To further investigate differences between A. sierrae and A.
magnus sp. nov. and the closely related A. zambalensis sp.
nov., we conducted a PCA of 18 craniodental measurements.
The first principal component (PC1), which accounted for
40% of the total variance, loaded heavily on nearly all
measurements, indicating that this is largely an indicator of
size and robustness; only width of zygomatic plate and
breadth of M1 loaded less strongly (Table 14). PC2 loaded
strongly (and positively) on length of the upper molar
toothrow, palatal breadth at M1, and breadth of M1 and
strongly (but negatively) on diastema length and postpalatal
length. Subsequent components had eigenvalues less than 1.2.
A plot of PC1 and PC2 (Fig. 38) shows that A. magnus sp.
nov. scored higher than A. sierrae on PC1 with limited
overlap, confirming its generally large size. There was
complete overlap on PC2. As noted below, A sierrae is easily
distinguished from A. zambalensis sp. nov. with the use of
qualitative features and some craniodental features; this
morphometric analysis shows that they do not differ in overall
size, but they generally differ on PC2, although with overlap,
confirming the utility of dental measurements, diastema
length, and postpalatal length in distinguishing most individuals, as discussed below. Given the extent of morphological
and genetic differences among these species, we regard each as
distinct from the others.
Apomys sierrae differs from A. aurorae sp. nov., its closest
geographic neighbor, usually in subtle ways, reflecting the
relatively close phylogenetic relationship evident in Figure 7.
Their external dimensions are similar; A. sierrae tends to have
a longer hind foot, but the means of other measurements are
similar (Fig. 39A; Tables 9, 11, 12, 15). The dorsal pelage is
rusty brown on both species, but has more of a yellow tint in
A. aurorae sp. nov. (Fig. 2F) and a more reddish tint in A.
sierrae (Fig. 2C). The ventral pelage of the two species is
similar. Dark hairs extend down further on the forelimbs of A.
sierrae, reaching the base of the paws, whereas there is only
white fur on the lower forelimbs and forepaws of A. aurorae
sp. nov. The dorsal surface of the hind foot of A. sierrae is
39
TABLE 11.
Cranial and external measurements (mean 6 1 S.D. and range) of Apomys sierrae (part).
Apomys sierrae
Mt. Cagua, 800 m,
Cagayan Prov.
Measurement
Basioccipital
length
Interorbital
breadth
Zygomatic
breadth
Mastoid breadth
Nasal length
Incisive foramen
length
Rostral depth
Rostral length
Orbitotemporal
length
Maxillary
toothrow
length
Labial palatal
breadth at M1
Diastema length
Postpalatal length
Lingual palatal
breadth at M3
Braincase height
Breadth of M1
Breadth of
incisors at tip
Width of
zygomatic plate
Length of head
and body
Total length
Length of tail
vertebrae
Length of hind
foot
Length of ear
Weight (g)
M (n = 4)
F (n = 1)
Mt. Lataan, 1200 m,
Quirino Prov.
M (n = 1)
F (n = 2)
M (n = 2)
F (n = 3)
35.70 6 1.44 (3)
34.67–37.35
6.17 6 0.26
5.82–6.41
17.52 6 0.42
16.97–17.96
14.14 6 0.18
14.02–14.41
14.67 6 0.50 (3)
14.36–15.24
5.30 6 0.08 (3)
5.23–5.39
7.57 6 0.19 (3)
7.42–7.78
15.45 6 0.27 (3)
15.19–15.72
12.16 6 0.32
11.76–12.48
7.41 6 0.22
7.15–7.60
35.98
—
6.30
—
17.66
—
14.23
—
15.12
—
5.87
—
7.70
—
15.19
—
12.84
—
7.29
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
7.69
—
35.18 6 1.09
34.41–35.95
5.98 6 0.11
5.90–6.05
17.93 6 0.89
17.30–18.56
13.68 6 0.35
13.43–13.93
14.49 6 0.17
14.37–14.61
4.96 6 0.06
4.91–5.00
7.55 6 0.47
7.22–7.88
15.03 6 0.01
15.02–15.03
12.21 6 0.32
11.98–12.43
7.64 6 0.01
7.63–7.65
34.60 (1)
—
6.15 6 0.25
5.97–6.32
18.24 6 0.47
17.90–18.57
14.27 6 0.13
14.18–14.36
14.36 (1)
—
5.24 (1)
—
7.40 (1)
—
14.70 (1)
—
12.13 6 0.71
11.63–12.63
7.72 6 0.27
7.53–7.91
34.73 6 0.75 (2)
34.20–35.26
6.15 6 0.04 (2)
6.12–6.18
18.06 6 0.23 (2)
17.89–18.22
14.06 6 0.69 (2)
13.57–14.54
14.27 6 0.02 (2)
14.25–14.28
5.73 6 0.01 (2)
5.72–5.73
7.79 6 0.11 (2)
7.71–7.86
14.95 6 0.49 (2)
14.60–15.29
12.14 6 0.09 (2)
12.08–12.20
8.01 6 0.17
7.82–8.15
7.57 6 0.23
7.31–7.83
9.62 6 0.69 (3)
8.83–10.12
11.88 6 0.62
11.50–12.81
5.24 6 0.04
5.20–5.30
10.99 6 0.33
10.63–11.35
1.81 6 0.11
1.70–1.93
2.19 6 0.07 (3)
2.12–2.26
3.50 6 0.20
3.22–3.69
132.4 6 9.4 (3)
122–141
271.0 6 19.3 (3)
250–288
138.6 6 9.9 (3)
128–147
33.2 6 1.8
32–36
18.8 6 0.3
18–19
84.3 6 8.3
78–96
7.98
—
9.99
—
11.82
—
5.33
—
10.45
—
1.94
—
2.30
—
3.59
—
—
—
277
—
—
—
32
—
19
—
106
—
7.81
—
—
—
—
—
—
—
—
—
1.97
—
—
—
—
—
133
—
262
—
129
—
33
—
20
—
66
—
7.76 6 0.42
7.46–8.05
9.52 6 0.50
9.17–9.87
11.70 6 0.51
11.34–12.06
5.42 6 0.34
5.18–5.66
10.54 6 0.62
10.10–10.97
1.99 6 0.00
1.99
2.34 6 0.02
2.32–2.35
3.79 6 0.01
3.78–3.80
149 (1)
—
296 (1)
—
139.3 6 10.3
132–147
34.0 6 0.0
34
20.0 6 0.0
20
79.0 6 17.0
67–91
8.05 6 0.26
7.86–8.23
9.06 (1)
—
11.81 6 0.29
11.60–12.01
5.37 6 0.33
5.13–5.60
10.81 6 0.72
10.30–11.32
2.04 6 0.04
2.01–2.07
2.19 (1)
—
3.85 6 0.00
3.85
143.0 6 8.5
137–149
286.5 6 19.1
273–300
143.5 6 10.6
136–151
36.5 6 2.1
35–38
21.0 6 0.0
21
86.0 6 14.1
76–96
7.98 6 0.26
7.75–8.27
9.13 6 0.21 (2)
8.98–9.27
11.19 6 0.25 (2)
11.01–11.36
5.49 6 0.33 (2)
5.26–5.72
10.64 6 0.16 (2)
10.52–10.75
2.03 6 0.07
1.95–2.08
2.24 6 0.06 (2)
2.19–2.28
3.61 6 0.22 (2)
3.45–3.76
134.7 6 4.0
131–139
274.0 6 12.3
265–288
139.3 6 8.4
134–149
35.0 6 2.0
33–37
20.0 6 1.0
19–21
79.3 6 13.6
64–90
primarily white, with a few scattered dark hairs, whereas that
of A. aurorae sp. nov. is either white or has scattered dark
hairs, except for having pure white adjacent to and on the toes.
Both species have a short hallux that reaches only about to the
bottom of the adjacent plantar pad. The two species are most
readily distinguished on the basis of the basicranial carotid
circulatory pattern. In A. sierrae, the foramen for the stapedial
artery in the bulla is absent (the ‘‘abrae pattern’’; Fig. 5A),
whereas in A. aurorae sp. nov., it is small but always present
(the ‘‘datae pattern’’; Fig. 5B). The configuration of the skulls
is similar, and the PCA of cranial measurements shows that
individuals of A. aurorae sp. nov. fall entirely within the plots
of A. sierrae (Fig. 33; Table 10). However, close inspection
40
Mungiao Mtns., 450 m,
Quirino Prov.
shows the skull of A. sierrae is slightly more elongate, usually
with a slightly shorter rostrum and orbitotemporal fossa
(Fig. 39C), and a braincase that is less broad. The maxillary
toothrows of A. sierrae usually are slightly narrower and they
diverge posteriorly to a greater degree than in A. aurorae sp.
nov. The zygomatic plate of A. sierrae tends to be narrower
than that of A. aurorae sp. nov. (Figs. 34, 39B). The
interparietal bones of the two species are variable, but usually
similar in width. The mandible of A. aurorae sp. nov. is slightly
deeper, and the posterior margin between the condylar and
angular processes is less concave. Although most differences
are slight, the discrete difference in the form of the carotid
circulatory system and the genetic monophyly of the two
TABLE 11. Extended.
Apomys sierrae
Mt. Palali, 700–839 m,
Nueva Vizcaya Prov.
M (n = 7)
Mt. Palali, 1052–1259 m,
Nueva Vizcaya Prov.
Mt. Palali, 1434–1443 m,
Nueva Vizcaya Prov.
F (n = 2)
M (n = 2)
F (n = 4)
M (n = 8)
F (n = 12)
36.13 6 0.78 (6)
35.52–37.52
6.23 6 0.19 (6)
6.05–6.54
18.76 6 0.50 (6)
18.05–19.55
14.83 6 0.59 (6)
13.99–15.36
15.15 6 0.29 (6)
14.70–15.46
5.98 6 0.27 (6)
5.57–6.34
8.03 6 0.35 (6)
7.68–8.63
15.98 6 0.21 (6)
15.70–16.32
12.43 6 0.31 (6)
12.13–13.03
7.52 6 0.31
7.21–8.09
35.25 6 0.40
34.97–35.53
6.24 6 0.21
6.09–6.38
17.75 6 0.26
17.56–17.93
14.21 6 0.27
14.02–14.40
15.03 6 0.40
14.75–15.31
5.35 6 0.08
5.29–5.40
7.74 6 0.27
7.55–7.93
15.53 6 0.26
15.35–15.71
12.11 6 0.40
11.82–12.39
7.29 6 0.02
7.27–7.30
35.19 6 2.01
33.77–36.61
6.13 6 0.46
5.80–6.45
18.47 6 0.71
17.96–18.97
14.78 6 0.21
14.63–14.92
14.44 6 0.73
13.92–14.95
5.47 6 0.06
5.43–5.51
7.75 6 0.40
7.46–8.03
15.34 6 0.82
14.76–15.92
11.95 6 0.74
11.43–12.47
7.51 6 0.16
7.39–7.62
34.57 6 0.70
33.55–35.12
6.13 6 0.38
5.57–6.38
18.34 6 0.80
17.45–19.18
14.30 6 0.48
13.97–15.01
14.03 6 0.53
13.58–14.73
5.35 6 0.26
5.02–5.57
7.50 6 0.20
7.21–7.68
15.07 6 0.61
14.40–15.84
12.05 6 0.32
11.58–12.30
7.36 6 0.18
7.16–7.60
34.68 6 0.75
33.49–35.63
6.05 6 0.19
5.76–6.32
18.18 6 0.22
17.84–18.58
14.43 6 0.16
14.28–14.73
14.26 6 0.41
13.49–14.83
5.41 6 0.34
4.68–5.78
7.57 6 0.19
7.26–7.80
14.87 6 0.53
13.95–15.34
11.84 6 0.43
11.10–12.17
7.62 6 0.17
7.25–7.81
35.07 6 0.70
34.44–36.80
5.91 6 0.16
5.64–6.22
18.36 6 0.55
17.42–19.48
14.45 6 0.38
13.88–15.35
14.43 6 0.37
13.76–15.03
5.40 6 0.31
4.78–5.84
7.55 6 0.16
7.32–7.81
15.06 6 0.39
14.40–15.69
12.07 6 0.33
11.39–12.65
7.61 6 0.22
7.13–8.00
8.16 6 0.29 (6)
7.73–8.49
9.78 6 0.43 (6)
9.39–10.51
11.94 6 0.59 (6)
11.35–13.08
5.55 6 0.25 (6)
5.06–5.77
10.64 6 0.39 (6)
10.07–10.99
1.96 6 0.09
1.87–2.14
2.17 6 0.13 (6)
2.05–2.40
3.65 6 0.13 (6)
3.49–3.79
150.0 6 11.5 (6)
136–171
291.7 6 11.5 (6)
275–304
141.7 6 12.1 (6)
124–154
36.0 6 1.8 (6)
34–39
20.2 6 1.0 (6)
19–21
91.6 6 12.3 (5)
80–111
7.99 6 0.11
7.91–8.07
9.47 6 0.30
9.25–9.68
11.67 6 0.21
11.52–11.82
5.57 6 0.07
5.52–5.62
10.89 6 0.06
10.85–10.93
1.95 6 0.12
1.86–2.03
2.12 6 0.03
2.10–2.14
3.35 6 0.02
3.33–3.36
142.5 6 0.7
142–143
275.0 6 0.0
275
132.5 6 0.7
132–133
36.5 6 2.1
35–38
19.0 6 1.4
18–20
86.5 6 10.6
79–94
8.21 6 0.44
7.90–8.52
9.09 6 1.02
8.37–9.81
11.66 6 0.79
11.10–12.22
5.67 6 0.46
5.34–5.99
11.12 6 0.37
10.86–11.38
1.93 6 0.09
1.87–1.99
2.10 6 0.32
1.87–2.32
3.52 6 0.45
3.20–3.83
141.5 6 7.8
136–147
278.5 6 21.9
263–294
137.0 6 14.1
127–147
36.0 6 0.0
36
19.0 6 0.0
19
85.0 6 12.7
76–94
7.97 6 0.26
7.73–8.21
9.41 6 0.50
8.89–10.09
11.29 6 0.36
10.80–11.67
5.61 6 0.45
5.08–6.15
10.50 6 0.43
10.01–11.02
1.93 6 0.05
1.87–1.98
2.09 6 0.11
2.02–2.25
3.46 6 0.15
3.32–3.65
138.0 6 2.2
136–141
278.3 6 7.4
270–287
140.3 6 5.3
134–146
35.8 6 1.0
35–37
19.7 6 1.2 (3)
19–21
74.5 6 6.4
70–84
7.88 6 0.18 (7)
7.62–8.05
9.23 6 0.41
8.55–9.99
11.27 6 0.47
10.43–11.89
5.51 6 0.19 (7)
5.32–5.84
10.72 6 0.22
10.52–11.10
1.97 6 0.04
1.91–2.04
2.13 6 0.06 (7)
2.06–2.22
3.50 6 0.19
3.18–3.69
138.3 6 6.3
128–147
271.0 6 10.4
254–283
132.8 6 7.3
123–146
35.4 6 2.1
31–38
19.4 6 0.9
18–21
79.6 6 7.6
64–90
7.88 6 0.20
7.55–8.25
9.33 6 0.34
8.97–10.17
11.56 6 0.36
11.00–12.34
5.39 6 0.17
5.10–5.68
10.77 6 0.22
10.31–11.11
1.99 6 0.09
1.84–2.10
2.30 6 0.09 (11)
2.12–2.51
3.45 6 0.27
2.85–4.05
139.1 6 6.0 (11)
130–149
276.9 6 9.9 (11)
254–285
137.8 6 7.0 (11)
124–147
35.8 6 1.5
33–38
19.3 6 0.8
18–20
86.8 6 8.2
72–100
groups leads us to hypothesize that they are discrete species,
and we treat them as such.
Apomys sierrae is easily distinguished from A. zambalensis
sp. nov., to which it is also closely related (Fig. 7). Apomys
sierrae averages smaller in nearly all respects; a plot of ear
length and hind foot length shows limited overlap (Fig. 40A).
The dorsal pelage of A. zambalensis sp. nov. is a rather bright
rusty umber (Fig. 2A), whereas that of A. sierrae is either a
dark, slightly reddish brown (in the Sierra Madre; Fig. 2C) or
a somewhat tawny brown (on Mt. Palali; Fig. 2D). The foreand hind feet of A. zambalensis sp. nov. have almost no dark
hairs on the dorsal surface, whereas A. sierrae virtually always
has at least some dark hairs. The ventral surface of the hind
foot of A. zambalensis sp. nov. is typically only moderately
pigmented and has large plantar pads, whereas A. sierrae
typically is heavily pigmented and has smaller pads. The
hallux of A. sierrae is short, reaching only to the bottom of the
adjacent plantar pad, whereas that of A. zambalensis sp. nov.
is long, reaching about to the top of the pad (Fig. 10E,I). The
cranium of A. zambalensis sp. nov. is larger than that of A.
sierrae, with a more robust rostrum, broader and more
squarish braincase, broader incisive foramina, narrower M1,
less divergent maxillary toothrows, less heavily pitted and
perforated palate, and longer postpalatal region. Bivariate
plots of postpalatal length vs. breadth of M1 (Fig. 40B) and
rostral depth vs. diastema length (Fig. 40C) taken in
combination allow separation of most individuals. The
interparietal bones in the two species are variable in shape
41
FIG. 34. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys sierrae sp. nov. (FMNH
but usually similar in width. The mandible of A. zambalensis
sp. nov. is deeper, with a somewhat more robust coronoid
process, broader angular process, and broader and slightly less
concave posterior margin between the condylar and angular
processes. The PCA described above (Fig. 38; Table 14) shows
no difference in size (PC1) but overlaps with substantially
different averages along PC2, which loads heavily on the
dental features, diastema length, and postpalatal length that
are individually apparent as differences. These metric differences, combined with the difference in carotid circulatory
pattern and clear genetic monophyly, lead us to conclude that
these are different species.
DISTRIBUTION—Specimens referred to this species have a
wide distribution, from Palaui Island off the NE tip of Luzon,
south through the main mass of the Sierra Madre mountain
range in Cagayan Province to Mt. Lataan and the Mungiao
Mountains in Quirino Province (Figs. 3, 35). We also refer
specimens from Mt. Palali, in the Caraballo Mountains of
Nueva Viscaya, to this species because they are genetically and
morphologically highly similar, except for having paler pelage.
Apomys sierrae probably has the broadest geographic range of
any species of Megapomys, although the ranges of A. abrae
and A. datae are nearly as large. The report by Danielsen et al.
(1994) of large Apomys tentatively referred to A. datae actually
refers to this species. The documented elevational range of the
species on Luzon is from ca. 475 to 1700 m, one of the greatest
among Apomys (Fig. 15), but we also recorded it at 153 m on
Palaui Island, which has a maximum elevation of about 300 m.
The distribution of this species and A. abrae, and possibly A.
datae, might overlap in the area where the Caraballo
42
Mountains and the Central Cordillera come into contact in
southwestern Nueva Vizcaya; surveys in that area should
produce interesting information about comparative habitat
use by these species.
Apomys (Megapomys) magnus sp. nov.
HOLOTYPE—FMNH 183574, adult female collected on 23
February 2005 by Danilo S. Balete, field number DSB 3606. A
sample of muscle tissue was removed from the thigh in the
field and preserved in ethanol before the specimen was
preserved in formaldehyde. In the museum, the skull was
removed and cleaned (see Methods). Palate damaged by
perforation, pterygoid process broken off and lost from left
side; otherwise, in good condition. This specimen will be
permanently deposited at the NMP. Measurements appear in
Table 12.
TYPE LOCALITY—Philippines: Luzon Island: Quezon Province: Tayabas Munic.: Barangay Lalo: Mt. Banahaw, Hasaan, 1250 m; 14u39440N, 121u31980E (from GPS).
PARATYPES (n 5 12)—Luzon Island: Quezon Prov.: Tayabas
Munic.: Brgy. Lalo: Idoro: Mt. Banahaw, 765 m (FMNH
183569–183572); Tayabas Munic.: Brgy. Lalo: Hasa-an: Mt.
Banahaw, 1250 m (FMNH 183573, 183575–183579); Tayabas
Munic.: Brgy. Lalo: Mt. Banahaw, 1465 m (FMNH 178395–
178396).
ETYMOLOGY—An adjective from the Latin magnus, meaning
‘‘large,’’ in recognition that it is the largest species of Apomys
currently known.
aurorae, A. magnus, A. sierrae, and A. zambalensis spp. nov. See
respective species accounts for localities. Shading on land areas, in
increasingly dark tones of gray: 0–500 m elevation; 501–1000 m;
1001–1500 m; 1501–2000 m; and white above 2000 m. Provincial
boundaries are shown for reference.
DIAGNOSIS AND DESCRIPTION—The largest species of Megapomys, with HBL averaging about 147 mm, and weight usually
98–108 g; some individuals weighed up to 128 g. The length of
the tail is typically 96–99% of the length of HBL. Apomys
magnus has dorsal fur of moderate length; it is dark brown
with conspicuous dark tips, with little evidence of orange or
yellow highlights (Fig. 1E). The ventral fur is medium gray at
the base, and white at the tips. The tail is unpigmented
ventrally and dark brown dorsally. The hind foot is the longest
of any Megapomys, averaging 39–40 mm; it is broad relative to
its length, the plantar pads are of moderate size, and the
ventral surface is moderately to heavily pigmented, with the
exception of the thenar pad (Fig. 10D). The toes are robust,
with the hallux reaching to about the top of the adjacent
interdigital plantar pad, and digit 5 reaching nearly to the base
of digit 4. The fur on the dorsal surface of the hind foot is
white or pale cream. On the forefoot, a stripe of dark hairs
extends along the median from the forearm to (or near to) the
base of the toes.
The cranium of A. magnus (Fig. 41) is the largest among
Megapomys, averaging about 37.4 mm in basioccipital length
and 19.3 in zygomatic width (Table 12). The rostrum is robust
and fairly long, and the incisive foramina are unusually long.
The braincase is broad and sturdy, and the zygomatic arches
are robust and flare to the sides. The maxillary toothrow is
long, and M1 is especially wide. The bony palate is broad and
the posterior portion has many small pits and perforations.
The postpalatal region is of average length. The basicranial
sierrae sp. nov. (see text and Table 13) based on specimens in
Tables 9, 11, and 12. 0 5 Mt. Cetaceo, Cagayan Province, ca. 1300 m;
1 5 Mt. Cetaceo, Cagayan Province, ca. 1500 m; 2 5 Palaui Island,
Cagayan Province; 3 5 Mt. Cagua, Cagayan Province; 4 5 Mt.
Lataan, Quirino Province; 5 5 Mungiao Mtns., Quirino Province; 6
5 Mt. Palali, Nueva Vizcaya Province, ca. 800 m; 7 5 Mt. Palali,
Nueva Vizcaya Province, ca. 1100 m; 8 5 Mt. Palali, Nueva Vizcaya
Province, ca. 1440 m; 9 5 Mt. Palali, Nueva Vizcaya Province,
1700 m.
circulation is of the ‘‘datae pattern’’ (Fig. 5B). The interparietal is variable in shape but is usually anteroposteriorly wide.
The mandible (Fig. 41C) is robust, with a coronoid process of
average length, a broad angular process, and a shallow
concave edge between the condylar and angular processes.
COMPARISONS—Apomys magnus differs from A. banahao in
the ways described above for that species, which occurs largely
above it in elevation on Mt. Banahaw, but occasionally in
sympatry (Fig. 15). In general, A. banahao has longer, softer
pelage, the hallux is short, the maxillary toothrow is shorter
and narrower, the palate is narrower (Fig. 29C), and the
bullae lack a foramen for the stapedial artery. Our genetic data
show them to be distantly related, confirming them as distinct
species.
Apomys magnus differs from A. sierrae as described above;
A. sierrae averages smaller, with little overlap in most external
and cranial measurements (Fig. 37), has dorsal fur that is dark
brown with rusty reddish tones and ventral fur that is dark
gray at the base and pale gray at the tip with an ochraceous
wash. The hallux of A. magnus is long, and that of A. sierrae is
short. The crania are usually easily distinguished using a
combination of several measurements (Fig. 37B,C), and the
stapedial foramen is large and conspicuous in A. magnus but
absent in A. sierrae. The metric differences are apparent in a
PCA that includes A. magnus, A. sierrae, and A. zambalensis,
discussed in the A. sierrae species account (Fig. 38; Table 14).
Apomys magnus differs from A. aurorae sp. nov., one of its
closest relatives, in being much larger in all external and
cranial measurements, often with little overlap (Fig. 42). The
dorsal fur of A. aurorae sp. nov. (Fig. 2F) is not as dark and
has a yellow tint that is absent in A. magnus (Fig. 1E), and A.
43
TABLE 12. Cranial and external measurements (mean 6 1 S.D. and range) of Apomys sierrae (part) and A. magnus.
Apomys magnus
Apomys sierrae
Mt. Palali, 1680–1700 m,
Nueva Vizcaya Prov.
Measurement
Zygomatic breadth
Mastoid breadth
Nasal length
Rostral depth
Rostral length
Diastema length
Postpalatal length
Lingual palatal breadth at M3
Braincase height
Breadth of M1
Length of head and body
Total length
Length of tail vertebrae
Length of hind foot
Length of ear
Weight (g)
M (n = 8)
F (n = 3)
Palaui Island,
Cagayan Prov.
M (n = 3)
35.44 6 0.96
33.65–36.34
6.31 6 0.20
6.09–6.68
18.76 6 0.69
17.65–19.63
14.67 6 0.17 (7)
14.50–14.96
14.60 6 0.58
13.84–15.50
5.61 6 0.45
5.07–6.34
7.72 6 0.26
7.15–7.96
15.43 6 0.30
14.97–15.86
12.31 6 0.70
11.33–13.12
7.61 6 0.17
7.29–7.80
8.14 6 0.30
7.67–8.46
9.54 6 0.30
9.08–10.01
11.43 6 0.37 (7)
10.97–11.94
5.60 6 0.15
5.40–5.78
10.91 6 0.43 (7)
10.31–11.57
1.97 6 0.05
1.91–2.05
2.22 6 0.07
2.10–2.33
3.47 6 0.08
3.35–3.58
143.1 6 7.3
132–151
279.1 6 13.4
261–295
136.0 6 9.5
121–149
36.6 6 1.6
35–40
20.0 6 0.8
19–21
78.6 6 7.3
69–90
35.21 6 0.18
35.02–35.36
6.17 6 0.09
6.08–6.25
18.89 6 0.10
18.78–18.95
14.43 6 0.27
14.20–14.72
14.54 6 0.13
14.39–14.64
5.63 6 0.50
5.10–6.09
7.80 6 0.28
7.49–8.02
15.34 6 0.15
15.19–15.49
12.44 6 0.33
12.08–12.73
7.42 6 0.12
7.29–7.50
7.99 6 0.30
7.65–8.22
9.35 6 0.42
8.86–9.60
11.14 6 0.25
10.85–11.29
5.40 6 0.24
5.13–5.57
11.04 6 0.52
10.68–11.63
1.90 6 0.15
1.76–2.05
2.30 6 0.18
2.13–2.49
3.57 6 0.24
3.29–3.75
144.3 6 2.1
142–146
280.7 6 2.1
279–283
136.3 6 4.0
134–141
34.7 6 1.2
34–36
19.3 6 0.6
19–20
92.0 6 13.9
84–108
35.14 6 0.33
34.76–35.33
6.16 6 0.25
5.90–6.40
17.59 6 0.73
16.96–18.39
14.11 6 0.23
13.84–14.26
14.29 6 0.55
13.66–14.63
5.39 6 0.29
5.07–5.63
7.52 6 0.18
7.33–7.68
14.94 6 0.10
14.83–15.01
12.09 6 0.35
11.71–12.40
7.07 6 0.05
7.03–7.13
7.09 6 0.13
6.95–7.20
9.37 6 0.21
9.24–9.62
11.88 6 0.14
11.73–12.01
4.91 6 0.31
4.63–5.24
10.48 6 0.04
10.44–10.51
1.78 6 0.04
1.73–1.81
2.18 6 0.08
2.09–2.24
3.50 6 0.08
3.41–3.55
142.0 6 7.2
134–148
279.7 6 8.5
271–288
137.7 6 2.1
136–140
35.3 6 0.6
35–36
20.0 6 1.0
19–21
83.3 6 11.0
72–94
aurorae sp. nov. lacks the dark tips on dorsal hairs that are
conspicuous on A. magnus. The ventral surface of the foot is
much darker on A. magnus than on A. aurorae sp. nov., and
the hallux of A. magnus reaches to about the top of the
adjacent interdigital plantar pad, whereas that of A. aurorae
sp. nov. reaches only to the base of the pad (Fig. 10G).
Bivariate plots of basioccipital length and interorbital breadth,
and of nasal length and rostral depth, show no overlap
between these species (Fig. 42B,C). The interparietal of A.
magnus is variable in shape but usually somewhat wider
anteroposteriorly than that of A. aurorae sp. nov. As described
in the species account for A. sacobianus, a PCA of that species
44
Mt. Banahaw,
765–1465 m,
Quezon Prov.
F-holotype
FMNH 183574
M (n = 3)
F (n = 6)
37.04
—
6.44
—
19.40
—
15.15
—
15.25
—
5.34
—
7.80
—
16.40
—
13.09
—
8.13
—
8.65
—
9.73
—
12.39
—
6.04
—
11.57
—
2.19
—
2.24
—
3.62
—
137
—
272
—
135
—
39
—
22
—
98
—
37.06 6 0.86
36.30–38.00
6.55 6 0.19
6.38–6.76
19.18 6 0.64
18.47–19.73
14.88 6 0.27
14.70–15.19
15.01 6 0.37
14.59–15.24
5.79 6 0.18
5.65–5.99
8.11 6 0.35
7.82–8.49
15.64 6 0.30
15.30–15.82
13.25 6 0.17
13.07–13.41
7.95 6 0.31
7.67–8.28
8.28 6 0.29
7.96–8.52
9.95 6 0.20
9.75–10.15
12.56 6 0.38
12.19–12.95
5.86 6 0.31
5.64–6.21
11.15 6 0.29
10.82–11.37
2.09 6 0.10
2.01–2.21
2.41 6 0.12
2.31–2.54
3.42 6 0.04
3.40–3.46
147.5 6 0.7 (2)
147–148
292.5 6 10.6 (2)
285–300
145.0 6 9.9 (2)
138–152
40.3 6 0.6
40–41
22.7 6 0.6
22–23
98.7 6 6.5
92–105
37.70 6 0.49
37.04–38.39
6.53 6 0.19
6.25–6.73
19.38 6 0.35
18.79–19.84
15.08 6 0.27
14.62–15.37
15.56 6 0.61
14.81–16.35
5.75 6 0.34
5.34–6.12
8.34 6 0.30
7.80–8.62
16.51 6 0.53
15.91–17.42
13.13 6 0.18
12.82–13.35
8.13 6 0.19
7.78–8.28
8.54 6 0.47
7.76–9.03
10.06 6 0.34
9.73–10.50
12.45 6 0.41
12.10–13.21
5.96 6 0.29
5.73–6.51
11.36 6 0.25
11.06–11.65
2.10 6 0.07
2.01–2.19
2.38 6 0.12
2.24–2.55
3.59 6 0.14
3.43–3.81
146.4 6 8.5 (5)
137–160
289.2 6 13.5 (5)
272–305
142.8 6 8.7 (5)
133–154
38.8 6 1.2
37–40
21.8 6 0.4 (5)
21–22
108.6 6 14.4 (5)
93–128
Mt. Banahaw,
765–1465 m, Quezon Prov.
plus A. aurorae sp. nov., A. magnus, and A. zambalensis sp.
nov. showed complete separation of A. magnus and A. aurorae
sp. nov. on a plot of PC1 and PC2, primarily reflecting their
consistent difference in overall size (Fig. 23; Table 7). This
difference, combined with their genetic monophyly, leads us to
treat them as different species.
Apomys magnus differs from A. zambalensis sp. nov.,
another close relative, in having longer dorsal fur with black
tips; A. zambalensis sp. nov. has fur that is a brighter, rusty
orange with only barely evident black tips. The ventral fur of
A. magnus is gray at the base and nearly white at the tips; that
of A. zambalensis sp. nov. is a paler gray at the base and white
FIG. 37. Bivariate plots of measurements comparing Apomys sierrae and A. magnus spp. nov. (A) Length of hind foot (HF) and weight
(WT). (B) Orbitotemporal length (OL) and postpalatal length (PPL). (C) Rostral depth (RD) and rostral length (RL).
at the tips with an ochraceous wash. The hind feet are similar,
but those of A. zambalensis sp. nov. are slightly smaller (39–40
vs. 37–38 mm) and less heavily pigmented (Fig. 10I). A plot of
weight vs. total length (Fig. 43A) shows that A. magnus is
usually longer and heavier, but there is overlap. A plot of the
width of M1 vs. breadth of incisors at the tip shows no overlap
(Fig. 43B), and length of the maxillary toothrow vs. labial
palatal breadth at M1 shows little overlap (Fig. 43C); A.
magnus is the larger in all of these measures. These metric
differences are apparent in a PCA that includes A. magnus, A.
sierrae, and A. zambalensis, discussed in the A. sierrae species
account, which shows no overlap between A. magnus and A.
zambalensis sp. nov. on the plot of PC1 vs. PC2 (Fig. 38;
Table 14). The combination of discrete morphological features, multivariate morphometric differences, and genetic
monophyly lead us to consider these to be clearly distinct
species.
DISTRIBUTION—Our elevational transect on Mt. Banahaw
documented this species from 765 to 1465 m in lowland and
montane rainforest (Figs. 15, 35). Extensive trapping at 620 m
failed to detect this species, and we doubt that it occurs below
about 700 m. We suspect that it occurs on Mt. Banahaw and
the adjacent Mt. San Cristobal (in Laguna and Quezon
provinces) from about 700 to about 1465 m elevation, in any
forested area. Above about 1465 m, we captured large
numbers of A. banahao, so we expect A. magnus to be absent
from high-elevation areas. Mts. Banahaw and San Cristobal
sit on a flat, low-elevation (below 300 m) plain, with scattered
peaks, largely below 1000 m, within 50 km in any direction.
We predict that this species will not be found in any other
areas, but surveys of the peaks in the general vicinity
(Batangas, Cavite, Laguna, and southern Quezon provinces)
would be worthwhile, especially at elevations above 700 m.
Apomys (Megapomys) aurorae sp. nov.
2006 by Phillip A. Alviola, field number PAA 864. A sample
of muscle tissue was removed from the thigh in the field and
preserved in ethanol before preserving the specimen in
formaldehyde. In the museum, the skull was removed and
TYPE LOCALITY—Philippines: Luzon Id: Aurora Province:
Dingalan Munic.: 2 km S, 2 km W Mingan peak, 1305 m,
15.46456uN, 121.38421uE (from GPS).
PARATYPES (n 5 98)—Luzon Island: Aurora Prov.: Dingalan Munic.: 2.25 km S, 3.25 km W Mingan peak, 733 m (FMNH
190933–190935); Dingalan Munic.: 2.1 km S, 2.9 km W
Mingan peak, 902 m (FMNH 190825, 190918–190932); Dingalan Munic.: 1.9 km S, 2.5 km W Mingan peak, 1074 m (FMNH
190826–190832, 190925, 190929); Dingalan Munic.: 2 km S,
2 km W Mingan peak, 1305 m (FMNH 190810, 190811, 190813–
190824, 190910–190917, 191067–191076); Dingalan Munic.:
1.8 km S, 1.6 km W Mingan peak, 1476 m (FMNH 190794–
190809, 190887–190909, 191066); Dingalan Munic.: 1.7 km S,
1.3 km W Mingan peak, 1540 m (FMNH 190953); Dingalan
analysis of log-transformed measurements of adult Apomys sierrae
(see Fig. 36 and Methods).
Principal component
Variable
1
0.824
0.567
Zygomatic breadth
0.723
Mastoid breadth
0.633
Nasal length
0.705
0.460
Rostral depth
0.719
Rostral length
0.767
0.672
20.009
0.635
Diastema length
0.696
Postpalatal length
0.556
Braincase height
0.290
0.127
Breadth of M1
0.391
0.335
Eigenvalue
6.032
33.51
2
3
4
20.266
20.325
0.263
0.120
20.009
0.010
0.086
20.158
20.100
0.701
0.675
20.434
20.478
0.389
20.004
0.782
0.029
0.288
2.514
13.96
0.099
0.207
0.064
0.219
20.338
20.137
20.217
20.289
0.002
0.328
20.123
20.110
0.203
20.178
0.697
20.026
0.595
0.000
1.416
7.87
20.250
0.272
0.299
0.383
20.171
20.485
20.010
0.015
20.380
20.395
0.078
0.126
20.305
0.421
0.046
20.224
20.007
0.034
1.283
7.13
45
analysis of log-transformed measurements of adult Apomys magnus,
A. sierrae, and A. zambalensis (see Fig. 38 and Methods).
Principal component
Variable
1
0.866
0.498
Zygomatic breadth
0.785
Mastoid breadth
0.695
Nasal length
0.745
0.526
Rostral depth
0.771
Rostral length
0.784
0.753
0.454
0.701
Diastema length
0.667
Postpalatal length
0.553
3
0.588
Braincase height
0.501
0.313
Breadth of M1
0.533
0.298
Eigenvalue
7.220
40.11
2
3
4
20.308
0.244
0.213
0.249
0.032
20.050
20.188
20.244
20.094
0.498
0.511
20.582
20.606
20.025
0.140
0.820
0.085
20.010
2.284
12.69
20.228
0.543
0.203
0.140
0.170
20.026
20.022
0.169
20.182
20.589
0.012
0.092
20.311
0.301
0.019
20.116
20.222
20.280
1.184
6.58
20.071
20.227
0.071
20.101
0.205
0.086
0.167
0.192
0.024
20.075
0.198
20.007
20.188
0.052
20.542
0.077
20.478
0.561
1.113
6.18
Munic.: 1.8 km S, 1.0 km W Mingan peak, 1677 m (FMNH
190846).
ETYMOLOGY—From the name of the province (Aurora)
where this species was captured; used as a noun in the genitive
case.
DIAGNOSIS AND DESCRIPTION—One of the smaller species of
Megapomys, although averaging only slightly larger than A.
minganensis, A. brownorum, and A. abrae in most measurements (Tables 2, 3, 9). The dorsal pelage of A. aurorae is rich,
rusty reddish-brown, with medium-gray underfur (Fig. 2F).
The ventral pelage is somewhat paler at the base, with the tips
either white or white with a pale ochraceous wash. The brown
pelage extends only a short distance onto the forearms and
lower hind legs, but scattered dark hairs are sometimes present
on the upper surface of the forefeet and hind feet. The ventral
surface of the hind feet is usually moderately darkly
pigmented, often including the pads, and the hallux is short,
reaching only to about the bottom of the adjacent interdigital
plantar pad (Fig. 10G). The tail is sharply bicolored and long,
averaging 98–100% of the length of the head and body. The
ventral surface of the tail is usually white, but some individuals
have scattered dark hairs and darkly pigmented scales.
The cranium (Fig. 44) has a somewhat globose braincase
that is less elongate than most species, a moderately short and
comparatively slender rostrum, a short diastema, and a short
postpalatal region. The molar toothrows are of average length
and width and diverge posteriorly, and the bony palate is
moderately broad. The stapedial foramen in the bulla for the
carotid artery is present in all individuals (the ‘‘datae pattern’’;
Fig. 5). The interparietal is variable in shape, but usually is
moderately wide anteroposteriorly. The mandible (Fig. 44C) is
of average depth with a relatively long and posteriorly curved
coronoid process. The angular process is broad and has a
blunt tip.
COMPARISONS—Apomys aurorae differs from A. minganensis
as described above; A. minganensis is darker dorsally and
46
sierrae, A. magnus, and A. zambalensis spp. nov. (see text and
Table 14) based on specimens in Tables 9, 11, 12, and 15.
ventrally, always has a tail with scattered dark hairs and
pigment ventrally, and has dark hair on the entire dorsal
surface of the hind feet. The hallux of A. aurorae is short,
reaching only to about the bottom of the adjacent interdigital
pad, whereas that of A. minganensis is long, reaching to about
the top of the pad. There is no overlap between these species in
rostral depth, orbital length, or length of the maxillary
toothrow, and there is little overlap in lingual breadth of the
palate at M3 (Fig. 31C). As described above, a PCA of
craniodental measurements that included A. aurorae, A.
minganensis, and A. sierrae (Fig. 33; Table 10) showed no
overlap in a plot of PC1 vs. PC2, with most of the differences
reflecting the features shown in Figures 31B and C. On the
basis of the qualitative and quantitative differences and the
genetic evidence of monophyly of these two populations, we
conclude that they represent distinct species.
Apomys aurorae differs from A. sierrae only in subtle ways,
as described above. They are most easily distinguished by the
presence of a foramen for the stapedial artery in the bullae of
A. aurorae (the ‘‘datae pattern’’; Fig. 5B) and its absence in A.
sierrae (the ‘‘abrae pattern’’; Fig. 5A). A PCA of craniodental
measurements (Fig. 33; Table 10), discussed above, showed
complete overlap on the two interpretable components, but
the difference in the stapedial foramen and the genetic
evidence of monophyly leads us to view these as distinct
species.
Apomys aurorae differs from A. magnus in being consistently
smaller in all external and cranial measurements, so it is easily
distinguished (Fig. 42). The carotid circulation pattern is the
same (the ‘‘datae pattern’’; Fig. 5B) in these two species. The
dorsal fur of A. aurorae (Fig. 2F) is not as dark and has a
yellow tint that is absent in A. magnus (Fig. 1E), and A.
aurorae lacks the dark tips on dorsal hairs that are
conspicuous on A. magnus. Apomys magnus has few or no
dark hairs on the dorsal surface of the hind foot, but some
individuals of A. aurorae have scattered dark hairs. FurtherFIELDIANA: LIFE AND EARTH SCIENCES
FIG. 39. Bivariate plots of measurements comparing Apomys sierrae and A. aurorae spp. nov. (A) Length of hind foot (HF) and length of
head and body (HBL). (B) Length of incisive foramen (LIF) and width of zygomatic plate (ZP). (C) Rostral length (RL) and orbitotemporal
length (OL).
more, the ventral surface of the foot is much darker on A.
magnus than on A. aurorae, and the hallux of A. aurorae is
short, reaching only to the bottom of the adjacent plantar pad
(Fig. 10G), whereas that of A. magnus is long, reaching to
about the top of the pad (Fig. 10D). Bivariate plots of
basioccipital length and interorbital breadth, and of nasal
length and rostral depth, show no overlap between these
species (Fig. 42B,C). The interparietal of A. aurorae is usually
somewhat smaller than that of A. magnus. A PCA of
craniodental measurements (Fig. 23; Table 7), discussed
above, showed no overlap on the first component, which
reinforces the consistent difference in size. Combined with the
qualitative features summarized here and the genetic evidence
of monophyly (Fig. 7), we conclude that these are distinct
species.
Apomys aurorae is similar in size to A. zambalensis sp. nov.
in some respects, but other features differ with little overlap.
The dorsal pelage of A. aurorae is darker brown (Fig. 2F),
whereas that of A. zambalensis sp. nov. is bright rusty orange
(Fig. 2A); the ventral fur of A. zambalensis sp. nov. has a
moderate to heavy ochraceous wash, whereas A. aurorae has
less of the ochraceous wash. The hind foot of A. zambalensis
sp. nov. is usually longer (Fig. 45A) and the ventral surface
less heavily pigmented, with a longer hallux than that of A.
aurorae (Fig. 10G,I). The cranium of A. zambalensis sp. nov. is
usually larger overall, with a deeper rostrum and longer
postpalatal region (Fig. 45B) and narrower M1, although
there is some overlap. A PCA of craniodental measurements
(Fig. 23; Table 7), discussed above, showed complete overlap
on the first component, which reinforces the overall similarity
in size. On the second component, which loaded heavily (and
positively) on diastema length and postpalatal length and
(negatively) on interorbital breadth, palatal breadth at M1,
and width of the zygomatic plate, the overlap between these
species was limited. Combined with the qualitative differences
summarized here and the genetic evidence of monophyly
(Fig. 7), we conclude that these are closely related but distinct
species.
DISTRIBUTION—Our elevational transect of the Mingan
Mountains documented this species from 733 to 1677 m
(Figs. 3, 15, 35; Balete et al., this volume). It was the most
abundant species along the transect from 902 to 1476 m. At
the low end of the transect, we captured none at our 559-m
sampling area, and at the high end, we captured only one at
FIG. 40. Bivariate plots of measurements comparing Apomys sierrae and A. zambalensis spp. nov. (A) Length of ear (EAR) and length of
hind foot (HF). (B) Breadth of M1 (BM1) and postpalatal length (PPL). (C) Rostral depth (RD) and diastema length (DL).
47
FIG. 41. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys magnus sp. nov. (FMNH
1540 m (plus 8 A. minganensis), one at 1677 m (plus 24 A.
minganensis), and none at 1681 or 1785 m (where A.
minganensis was common). We infer that this species may be
expected throughout the Mingan Mountains from about 700
to 1675 m, with no Megapomys below 700 m and only A.
minganensis above about 1700 m.
No specimens of A. aurorae are currently available other
than from our transect (Fig. 35), so the extent of its
distribution is uncertain. The Mingan Mountains lie in the
central portion of Aurora Province and the adjacent area of
Nueva Ecija Province (Fig. 3). Areas of low elevation lie to the
north and to the south of the Mingan Mountains, with passes
at ca. 250 and 300 m, respectively, which is well below the
lower elevational limit currently documented for this species;
thus, the Mingan Mountains appear to function as a habitat
island for this species. There are specimens of A. sierrae from
northern Aurora Province and from Nueva Vizcaya, just to
the north of the Mingan Mountains (Fig. 35), so we predict
that A. aurorae will not be found to the north of the Mingan
Mountains (i.e., not north of the road that goes from
Bongabon, Nueva Ecija, to Baler, Aurora). Beyond the low
pass to the south (south of Gabaldon, Nueva Ecija, and
Dingalan, Aurora), there are no known specimens of
Megapomys from a long, rugged section of the southern
Sierra Madre that has Mt. Irid and Mt. Angilo as the high
points (in Rizal and nearby Quezon provinces; Fig. 3). Since
FIG. 42. Bivariate plots of measurements comparing Apomys magnus and A. aurorae spp. nov. (A) Length of hind foot (HF) and weight
(WT). (B) Basioccipital length (BOL) and interorbital breadth (IB). (C) Nasal length (NL) and rostral depth (RD).
48
FIG. 43. Bivariate plots of measurements comparing Apomys magnus and A. zambalensis spp. nov. (A) Weight (WT) and total length (TL).
(B) Breadth of M1 (BM1) and breadth of incisors at tip (BIT). (C) Length of maxillary molariform toothrow (M1–M3) and labial palatal breadth
at M1 (PBM1).
the peaks in this region reach well over 1000 m, Megapomys
should be present and should be sought to determine whether
A. aurorae occurs there, or whether yet another, currently
unknown species of Megapomys is present.
Apomys (Megapomys) zambalensis sp. nov.
HOLOTYPE—FMNH 183420, adult female collected on 25
March 2005 by Lawrence R. Heaney, field number LRH 7339.
specimen will be permanently deposited at the NMP. Measurements in Table 15.
TYPE LOCALITY—Philippines: Luzon Id.: Bataan Province:
0.1 km N Mt. Natib peak, 1150 m, 14.71513uN, 120.39892uE
(GPS reading).
FIG. 44. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys aurorae sp. nov. (FMNH
49
TABLE 15. Cranial and external measurements (mean 6 1 S.D. and range) of Apomys aurorae and A. zambalensis.
Apomys zambalensis
Apomys aurorae
Mingan Mtns., 733–1677 m, Aurora Prov.
Mt. Natib, Bataan Prov.
M-holotype
Mt. Tapulao, 860–1690 m,
Zambales Prov.
F-holotype
Measurement
190812
M
(n = 12)
Basioccipital
length
Interorbital
breadth
Zygomatic
breadth
Mastoid breadth
35.25
—
5.81
—
18.15
—
14.40
—
14.18
—
5.57
—
7.38
—
15.00
—
12.41
—
7.42
—
35.23 6 0.49
34.61–36.25
6.08 6 0.15
5.81–6.34
18.09 6 0.33 (11)
17.61–18.53
14.25 6 0.17
13.98–14.53
14.03 6 0.31
13.33–14.36
5.49 6 0.31
5.04–6.10
7.40 6 0.14
7.22–7.65
15.22 6 0.36
14.77–15.74
12.47 6 0.48
11.57–13.21
7.52 6 0.16
7.29–7.79
34.87 6 0.65
33.88–36.51
6.12 6 0.20
5.66–6.42
18.13 6 0.57
17.34–19.27
14.35 6 0.20
14.11–14.73
13.76 6 0.34
13.11–14.44
5.41 6 0.21
5.08–5.83
7.53 6 0.18
7.22–7.72
15.40 6 0.27
14.97–15.79
12.31 6 0.33
11.86–12.92
7.39 6 0.25
7.09–8.01
36.99
—
6.29
—
18.13
—
14.74
—
14.26
—
5.67
—
7.81
—
15.64
—
12.36
—
7.41
—
35.78 6 1.16
34.61–38.14
5.92 6 0.13
5.70–6.09
17.95 6 0.43
17.29–18.76
14.35 6 0.35
13.78–15.00
14.11 6 0.45
13.34–14.97
5.45 6 0.29
4.81–5.83
7.72 6 0.16
7.54–8.08
15.41 6 0.58
14.74–16.35
12.20 6 0.46
11.58–13.22
7.46 6 0.24
7.10–7.81
8.04
—
9.37
—
11.52
—
5.44
—
10.65
—
1.96
—
2.36
—
3.81
—
7.88 6 0.19
7.60–8.21
9.43 6 0.23
9.15–9.86
11.62 6 0.31
11.26–12.17
5.41 6 0.21
5.16–5.94
10.78 6 0.40
10.03–11.29
1.95 6 0.07
1.87–2.06
2.20 6 0.10
2.08–2.36
3.80 6 0.16
3.55–4.07
7.84 6 0.21
7.61–8.23
9.42 6 0.37
9.07–10.30
11.43 6 0.32
10.83–11.83
5.59 6 0.19
5.27–5.84
10.78 6 0.37
10.21–11.50
1.88 6 0.05
1.82–1.96
2.14 6 0.10
1.96–2.28
3.80 6 0.25
3.40–4.19
8.05
—
10.05
—
13.20
—
6.23
—
11.22
—
1.70
—
2.25
—
3.34
—
7.78 6 0.20 7.81 6 0.26
7.41–8.13
7.30–8.09
9.74 6 0.42 9.77 6 0.32
9.14–10.66
9.12–10.18
12.59 6 0.52 12.62 6 0.48
11.94–13.38 11.72–13.20
5.49 6 0.26 5.61 6 0.31
5.16–5.93
5.19–6.23
10.82 6 0.31 10.84 6 0.20
10.23–11.26 10.45–11.22
1.82 6 0.07 1.76 6 0.09
1.73–1.94
1.62–1.96
2.22 6 0.10 2.22 6 0.14
2.11–2.40
1.91–2.38
3.56 6 0.24 3.53 6 0.20
3.19–3.87
3.20–3.91
7.71 6 0.12
7.68 6 0.28
7.45–7.84
7.25–8.17
9.78 6 0.44
9.80 6 0.32
9.11–10.49
9.39–10.19
12.18 6 0.49 (8) 12.04 6 0.59
11.71–13.20
11.17–13.08
5.44 6 0.30 (9) 5.62 6 0.19
4.98–5.95
5.32–5.97
10.86 6 0.30
10.72 6 0.28
10.46–11.46
10.31–11.19
1.81 6 0.09
1.74 6 0.10
1.59–1.92
1.58–1.91
2.15 6 0.10
2.19 6 0.10
2.00–2.27
2.03–2.33
3.52 6 0.21
3.64 6 0.35
3.19–3.81
3.18–4.17
145.3 6 6.7 147.7 6 9.0 (12)
134–156
129–163
283.9 6 13.7 286.9 6 15.8 (12)
263–306
264–311
138.7 6 9.8 139.3 6 8.8 (12)
125–158
123–149
38.1 6 1.3
38.0 6 0.9
36–40
37–39
21.8 6 0.9
21.9 6 0.8 (11)
21–23
21–23
88.7 6 12.9 93.4 6 10.6
74–112
74–108
139.6 6 6.5 (9)
131–148
278.9 6 11.6 (9)
256–290
141.2 6 9.2
125–158
37.1 6 1.2
36–39
21.1 6 0.6 (9)
20–22
84.2 6 11.1
70–105
FMNH
Nasal length
Incisive foramen
length
Rostral depth
Rostral length
Orbitotemporal
length
Maxillary
toothrow
length
Labial palatal
breadth at M1
Diastema length
Postpalatal
length
Lingual palatal
breadth at M3
Braincase height
Breadth of M1
Breadth of
incisors at tip
Width of
zygomatic
plate
Length of head
and body
Total length
Length of tail
vertebrae
Length of hind
foot
Length of ear
Weight (g)
145
—
287
—
142
—
36
—
20
—
80
—
143.5 6 4.7
137–152
285.2 6 8.2
273–295
141.7 6 5.3
136–153
35.6 6 0.8
34–37
19.8 6 0.8
18–21
81.2 6 5.9
71–92
F
(n = 12)
183420
M
(n = 12)
(11) 136.9 6 6.0
126–144
(11) 272.7 6 9.0
262–285
(11) 135.5 6 5.7
129–147
34.7 6 0.9
33–36
20.0 6 0.7
19–21
(11) 73.8 6 6.3
58–83
FMNH
(11) 158
—
(11) 306
—
148
—
39
—
(9) 22
—
(11) 105
—
PARATYPES (n 5 231)—Luzon Island: Bataan Prov.: 0.1 km
N Mt. Natib peak, 1150 m (FMNH 183389, 183391, 183392,
183414–183416, 183418, 183421–183424); 0.3 km N, 0.1 km W
Mt. Natib peak, 1000 m (FMNH 183382–183386, 183388,
183390, 183405–183413, 183417, 183419, 183425); 0.7 km N,
0.2 km W Mt. Natib peak, 900 m (FMNH 183341–183381,
183387, 183393–183404).
Zambales Prov.: Palauig Munic.: Brgy. Salasa, Mt. Tapulao, 860 m (FMNH 178310, 178326–178330); Palauig Munic.:
Brgy. Salasa, Mt. Tapulao, 925 m (FMNH 183529–183545);
Palauig Munic.: Brgy. Salasa, Mt. Tapulao, 1200 m (FMNH
50
F
(n = 13)
M
(n = 10)
36.04 6 0.99
34.28–37.12
5.82 6 0.20
5.51–6.29
18.15 6 0.58
17.20–19.21
14.40 6 0.33
13.89–14.75
14.22 6 0.41
13.67–15.06
5.36 6 0.31
4.89–5.87
7.80 6 0.23
7.31–8.14
15.31 6 0.59
14.42–16.19
12.08 6 0.41
11.03–12.75
7.53 6 0.40
7.11–8.47
35.43 6 0.95
34.30–37.25
6.14 6 0.20
5.81–6.54
18.30 6 0.52
17.49–19.37
14.10 6 0.23
13.82–14.38
14.29 6 0.46
13.70–15.08
5.30 6 0.29
4.88–5.77
7.90 6 0.29
7.64–8.63
15.69 6 0.43
15.17–16.70
12.40 6 0.27
11.95–12.70
7.38 6 0.19
6.96–7.68
F
(n = 8)
35.46 6 1.18
33.51–37.43
5.94 6 0.20
5.67–6.28
18.27 6 0.42
17.58–18.80
14.13 6 0.39
13.74–14.73
14.27 6 0.52
13.42–14.89
5.63 6 0.40
5.30–6.30
7.81 6 0.24
7.61–8.32
15.51 6 0.64
14.77–16.34
12.54 6 0.52
11.51–13.31
7.40 6 0.16
7.13–7.57
139.6 6 6.9 (7)
127–150
277.9 6 10.3 (7)
265–295
138.3 6 5.3 (7)
129–145
36.8 6 0.9
35–38
21.6 6 0.5 (7)
21–22
87.4 6 9.1
67–95
178276–178292, 178331–178333, 178338–178343, 179434–
179442); Palauig Munic.: Brgy. Salasa, Mt. Tapulao, 1690 m
(FMNH 178293–178309, 178311–178325, 178334–178337,
178344–178357).
ETYMOLOGY—An adjective from the name of the province,
Zambales, from which the majority of the specimens
originated, and the name of the geological region (the
Zambales Range) that includes the type locality.
DIAGNOSIS AND DESCRIPTION—Apomys zambalensis is the
second largest known species of Megapomys, with a total
length averaging 278–289 mm and weight averaging 84–94 g
FIG. 45. Bivariate plots of measurements comparing Apomys aurorae and A. zambalensis spp. nov. (A) Length of hind foot (HF) and weight
(WT). (B) Rostral depth (RD) and postpalatal length (PPL). (C) Breadth of M1 (BM1) and interorbital breadth (IB).
(Table 15). The tail is typically 94–100% of the length of the
head and body, making it one of the longest-tailed species in
the subgenus. The dorsal fur is shorter and paler than that of
most species, with a bright rusty-orange appearance (Fig. 2A).
The ventral fur is pale to medium gray at the base, and white
with an ochraceous wash at the tips that varies between
individuals from slight to heavy. The ears are large, usually
22–23 mm, and less heavily pigmented than those of most
other Megapomys. The tail is sharply bicolored, heavily
pigmented dorsally but nearly white ventrally. The rustybrown dorsal color extends onto the forelimb in a dark stripe
that is bounded by pale orange, barely reaching to the base of
the foot. The hind foot is long (usually 36–39 mm) and broad,
with digit 5 reaching nearly to the middle joint of digit 4. It is
nearly white dorsally, sometimes with a few dark hairs. The
ventral side of the hind foot is lightly pigmented, with some
pigment on interdigital pad 4 and the hypothenar. The hallux
is long, reaching about to the top of the adjacent interdigital
pad (Fig. 10I).
The skull of A. zambalensis (Fig. 46) is large, with
basioccipital length averaging 34–38 mm (Table 15); only that
of A. magnus is larger overall. The rostrum is long and robust,
FIG. 46. Dorsal (A), ventral (B), and lateral (D) views of the cranium and lateral view of the mandible (C) of Apomys zambalensis sp. nov.
51
and the braincase is sturdy and somewhat elongate and
flattened. The incisive foramina are unusually broad, especially in the posterior portions. The bony palate is of typical
width and is moderately heavily pitted over its posterior
portion. The maxillary toothrows are of roughly average
length and width and diverge slightly posteriorly. The
postpalatal region is elongated. The foramen in the bulla for
the stapedial artery is relatively large and conspicuous (the
‘‘datae pattern’’; Fig. 5B). The interparietal is variable in
shape but usually is wide anteroposteriorly. The mandible
(Fig. 46C) is average in depth, with a shorter than average
coronoid process, average angular process, and rather deep
concavity between the condylar and angular processes.
As noted above, the analysis of mitochondrial DNA shows
only slight divergence between our two samples from Mt.
Tapulao and Mt. Natib (Fig. 7). A PCA of craniodental
measurements, discussed above (Fig. 23; Table 7) that included the closely related A. aurorae and A. magnus, as well as the
holotype of the geographically adjacent A. sacobianus, showed
virtually complete overlap of individuals from these two
mountains on both the first component, which primarily
indicated size, and the second component, which loaded
heavily (and positively) on diastema length and postpalatal
length and (negatively) on interorbital breadth, palatal
breadth at M1, and width of the zygomatic plate. Additionally,
we are unable to detect any discrete cranial features to
separate these samples. On the basis of these genetic and
morphological data, we consider these populations to
represent a single species, and we predict that individuals
from geographically intermediate populations will bridge the
current slight genetic gap between northern and southern
populations.
The karyotype of A. zambalensis on the basis of eight males
and seven females from Mt. Natib, Bataan Province (FMNH
183361, 183362, 183364, 183367, 183368, 183370–183373,
183376–183379, 183387, 183391), has 2n 5 44, FN $ 58
(Fig. 8C). The autosomal complement consists of two pairs of
large submetacentric, two pairs of medium-sized subtelocentric,
two pairs of very small metacentric or submetacentric, and 15
pairs of small to large-sized telocentric or subtelocentric
elements. The X chromosome is medium-sized and submetacentric, and the Y chromosome is small and telocentric.
COMPARISONS—Apomys zambalensis is easily distinguished
externally from other Megapomys by its large size, comparatively pale, bright rusty-brown fur, and pale ears and ventral
surface of the hind feet. Similarly, the skull is easily
distinguished by its large size, exceeding all species except A.
magnus. Apomys zambalensis is easily distinguished from its
closest relative, A. aurorae, as described above; A. aurorae is
smaller, with darker brown dorsal fur, dark hairs on the dorsal
side of the hind foot and more heavily pigmented soles, a short
hallux, a longer and more robust rostrum and braincase
(Fig. 45), and a larger stapedial foramen in the bulla. As
reflected in the PCA (Fig. 23; Table 7) of A. zambalensis, A.
aurorae, A. magnus, and A. sacobianus, A. zambalensis
typically differs from A. aurorae in having a narrower M1
and low braincase, but longer diastema, incisive foramina, and
postpalatal region (Fig. 45). The hallux of A. zambalensis is
long, whereas that of A. aurorae is short (Fig. 10G). Both A.
zambalensis and A. aurorae possess the ‘‘datae pattern’’ of
basicranial circulation (Fig. 5B), but A. aurorae has a smaller
stapedial foramen than A. zambalensis.
52
Apomys zambalensis differs from A. magnus, also closely
related, as described above under that species; A. magnus is
slightly larger and generally darker, with dark ears and dark
soles on the hind feet, with a broader M1, longer maxillary
toothrow, and broader palate (Fig. 43). These differences are
clearly apparent in a PCA of craniodental measurements
(Fig. 23; Table 7).
As described above, A. sierrae is somewhat smaller than A.
zambalensis in external features and is much darker dorsally
and ventrally, with much dark hair on the dorsal surface of the
hind foot and dark pigment on the ventral surface, and it has a
short hallux. Apomys sierrae has the ‘‘abrae pattern’’ of
basicranial carotid circulation (Fig. 5A) and is smaller in
breadth of M1, postpalatal length, and diastema length
(Fig. 40). The PCA of craniodental measurements described
above (Fig. 38; Table 14) shows no difference in size (PC1);
there is overlap, but with substantially different averages along
PC2, which loads heavily on the dental features, diastema
length, and postpalatal length that are individually apparent as
differences. Given these morphological differences and the clear
evidence of genetic monophyly and intervening species in the
phylogeny, we conclude that they represent distinct species.
DISTRIBUTION—We have documented A. zambalensis along
our elevational transects on Mt. Tapulao from 860 to 1690 m
and on Mt. Natib from 900 to 1150 m (Figs. 15, 35; Balete et
al., 2009). We had no sampling areas below these elevations on
either transect, so we do not know the lower limit of the
species’ distribution with certainty; because it was common at
our lowest sites, we suspect that it also occurs somewhat
lower. The upper boundary is also uncertain, because we have
no data between 1690 and 2024 m, but we suspect that it lies
near 1800 m, the elevation at which primary mossy forest
begins (Balete et al., 2009). We lack data from other
mountains in this region, but the presence of A. zambalensis
on Mts. Tapulao and Natib (Figs. 3, 35) leads us to suspect
that it occurs throughout the Zambales Mountains and on Mt.
Mariveles on the Bataan Peninsula at elevations above about
700 m. If this is so, it makes A. zambalensis one of the more
widely distributed species of Megapomys.
Discussion
The Status of Discovery of Philippine Mammalian Diversity
The discovery and description of seven previously unknown
species of mammals may surprise some people, especially since
all but one come from within 150 km of Manila (Fig. 3), a
metropolitan area with roughly 15 million people, and
especially in the current millennium, when it is widely assumed
that, although some less conspicuous organisms are poorly
known, mammals have generally been well documented. Our
studies in the field and museum show that this widespread
assumption is not well-founded. With one species of Archboldomys (Balete et al., 2006), two species of Rhynchomys
(Balete et al., 2007), and a new genus and species of mouse
(Musseromys gulantang; Heaney et al., 2009) already described
from the same areas on Luzon, as well as our ongoing studies
indicating that many additional new species in other genera
were obtained in the same surveys, it is clear that a great deal
of the mammalian diversity on Luzon, and perhaps in the
Philippines as a whole, has been unknown to the scientific and
conservation communities in the past, and it is likely that
many species remain unknown.
One might ask how long this poor state of knowledge will
persist in the future. Our studies of Luzon mammals have been
conducted in the context of predictive biogeographic models
and thus have been focused on those places most likely to
result in the discovery of new biological diversity. We predict
that locally endemic mammals will be found on individual
mountains or on mountain ranges that reach above 1000 m
elevation and are isolated from other such mountainous areas
by elevations below 300 m that are at least 10 km wide
(Heaney & Rickart, 1990; Heaney et al., 2000; Heaney, 2001,
2004; Rickart et al., 2010). Although our field surveys are not
yet complete, we predict that within a few more years, few
scientifically unknown mammals will remain on Luzon, with
one exception. Because our models are discrete and predictive,
they can be (and are being) tested, and so our prediction of a
declining curve of discovery will soon be either validated or
falsified. Thus, on the basis of current and planned surveys, we
will soon know whether mammalian diversity on Luzon is well
documented or whether our models were incorrect, and
therefore an unknown, but potentially great, number of
species remains to be found.
The one exception noted above refers to insectivorous bats.
This group is notoriously difficult to capture using our
standard sampling procedure, the use of mist nets, and we
know that some ‘‘species’’ are actually groups of cryptic
species (e.g., Ingle & Heaney, 1992; Sedlock & Weyandt,
2009). We explicitly acknowledge that we have not documented this group adequately and look forward to the results of the
increased use of alternative methods (such as bat traps, V-nets,
and tunnel traps; e.g., Alviola, 2008; Sedlock et al., 2008, this
volume; Alviola et al., this volume; Balete et al., this volume)
and evaluations using molecular genetics.
This discussion has referred only to the mammals of Luzon
Island. The predictive biogeographic models that we have
developed (Heaney & Rickart, 1990; Heaney, 2000, 2001,
2004; Rickart et al., 2011) refer to geographic features (e.g.,
elevational patterns of distribution, elevation of mountains,
degree of isolation of mountains, etc.) that are relevant to
other still very incompletely surveyed areas in the Philippines.
Our discovery of a previously unknown species of Batomys
from southeastern Mindanao (Balete et al., 2008) is consistent
with the patterns we have noted on Luzon, and it implies that
many subcenters of mammalian endemism, and therefore
many currently unknown species of mammals, remain to be
documented on Mindanao. The recent description of Crocidura panayensis from Panay Island (Hutterer, 2007) implies to
us that similar conditions exist on the islands that formed large
aggregate islands during Pleistocene periods of low sea level
and suggests that similarly intensive surveys of mammalian
diversity on those islands are warranted.
Geographic Distribution Patterns in Megapomys
The distribution of species in the subgenus Megapomys is
distinctly nonrandom, with six patterns that can be readily
identified at this time.
1) Species of Megapomys extend from northernmost Luzon
to Mt. Banahaw, but no further south on Luzon (Fig. 3).
Intensive surveys of small mammals on the Bicol
Peninsula of southern Luzon, on Mt. Labo, Saddle Peak,
Mt. Isarog, Mt. Malinao, and Mt. Bulusan, using the same
techniques that easily capture them in central and northern
Luzon, have failed to capture any Megapomys, although
the smaller species of Apomys are often present and
common (Rickart et al., 1991; Balete & Heaney, 1997;
Heaney et al., 1999; L. R. Heaney, unpubl. data and
specimens, FMNH). The elevation of the highest point
connecting the Bicol Peninsula and central Luzon is only
about 4 m above sea level, and this area of low elevation is
extensive, thus significantly isolating the mountains of
southern Luzon from those of central and northern Luzon.
2) All of the species of Megapomys occur on Luzon only at
elevations above 450 m, with few records below 800 m
(Fig. 15), even in areas of dense sampling effort where
forest is present (e.g., the Sierra Madre; Duya et al., 2007).
The one possible exception is A. sacobianus, known from a
single specimen taken near the Sacobia River ‘‘just above
the point where it emerges from the foothills of the
Zambales Mountains onto the plains of Pampanga’’
(Johnson, 1962). From maps of the area, we estimate this
to be 300 m. Each of the mountain masses has one or more
species of Megapomys from this lower point up to the
highest peak of the mountain. These data suggest that the
large areas of Luzon below 450 m do not, and did not
before deforestation, support populations of Megapomys
(except perhaps rarely between 450 and 300 m). On the
other hand, every mountain mass with a peak above about
1000 m that has been intensively surveyed has at least one
species present. Clearly, the species of Megapomys are
principally animals of montane and mossy forest. We
note, however, that A. sierrae has been documented on
Palaui Island, a small island off the NE tip of Luzon, at ca.
150 m. Specimens of A. sierrae have been taken only above
about 750 m in the adjacent areas of Cagayan Province on
Luzon Island. We suspect the lower elevational range is
associated with the fact that Palaui is a small island with
reduced species richness, as seen among small mammals
on Dinagat and Siargao islands, which lie off the NE coast
of Mindanao (Heaney and Rabor, 1982: Heaney et al.,
1998); further study is needed.
3) Each species of Megapomys is associated with a single
mountain range or individual mountain that is isolated
from other such mountains by lowland areas at 300 m or
lower. Each such mountainous area is thus an island of
montane or mossy forest habitat in a ‘‘sea’’ of lowland
forest (or, in recent centuries, agricultural lands). In cases in
which the mountain range is very extensive, as with the
Central Cordillera and the Sierra Madre, the species are
similarly widespread (i.e., A. abrae, A. datae, and A.
sierrae). In cases in which the mountain range is somewhat
smaller, such as the Zambales Mountains (which in this case
we define to include the mountains of the Bataan
Peninsula), the range is smaller (i.e., A. zambalensis). In
cases in which the mountain range is very small, the range
of the species is very small (e.g., A. minganensis and A.
aurorae in the Mingan Mountains and A. banahao and A.
magnus on Mt. Banahaw). The only exception to this
pattern currently evident is the occurrence of A. zambalensis
on Mt. Natib (on the Bataan Peninsula) and on the
Zambales Mountains, which are separated from one
another by a lowland area that drops to about 200 m.
However, the distance along the highest ridge connecting
Mt. Natib to Zambales that is below 450 m is less than
53
10 km wide and is made up of fairly steep, rugged slopes,
not flat lowlands. This might provide some clue as to the
precise conditions that prevent the movement of Megapomys from one mountain mass to another.
4) Two species of Megapomys occur on mountains over most
of central and northern Luzon, although which species are
present varies between mountain masses (Fig. 15). In the
Central Cordillera, A. abrae occurs from about 900 to
2200 m, and A. datae from about 1500 m to higher than
2800 m. The former occurs most often in relatively open
(often disturbed) and drier habitats, and the latter in more
mature, moister forest (Rickart et al., 2011). On Mt.
Banahaw, A. magnus occurs from about 800 to 1465 m,
and A. banahao from 1465 m up to at least 1800 m. In the
Mingan Mountains, A. aurorae occurs from about 750 to
ca. 1550 m, and A. minganensis from 1550 to 1750 m. In
the Zambales Mountains, A. zambalensis occurs from
about 850 to about 1750 m, and A. brownorum near the
peak at about 2050 m. These data show that over most of
central and northern Luzon, two species of Megapomys
usually occur on any given mountain mass, with one
species occurring from the lower limits of montane forest
elements (which begin to appear at about 500 m, but often
are sparse and widely scattered below 800 m) up to the
beginnings of prime mossy forest at about 1500 m, and the
other species occurring in mossy forest from about 1500 m
up to the peak. Current data are limited, but they suggest
that the species at the lower elevation will often occur in
more open and drier habitat at the upper edge of their
ranges and that syntopy between individuals of the two
species will be present but not extensive.
5) Species that occur within the same mountain mass are not
sister-species and most often are rather distantly related
(Fig. 7). For example, on Mt. Banahaw (A. banahao and
A. magnus) and the Zambales Mountains (A. brownorum
and A. zambalensis), the co-occurring pairs are distantly
related to one another. In the Mingan Mountains, A.
aurorae and A. minganensis are more closely related, but
they are still separated by considerable genetic distance
and several nodes in the phylogenetic tree. Only in the
Central Cordillera is this pattern not directly supported:
A. abrae and A. datae appear to be sister-taxa on the basis
of Figure 5, but we question the accuracy of the
mitochondrial data in this case because our preliminary
nuclear sequence data indicate that they are more distantly
related (S. J. Steppan, unpubl. data). Instead of close
relatives occupying nearby localities in the same mountain
region, they occupy similar elevations in different mountains.
6) There appears to be considerable ecological conservatism,
with all but one (A. abrae) of the species in clades B and C
(Fig. 7) occurring in high-elevation mossy forest and all
but one (A. minganensis) of the species in clade D
occurring in montane forest, primarily below 1500 m.
This pattern suggests diversification among Megapomys
within particular portions of the elevational gradient
throughout northern and central Luzon.
Taken together, these six patterns imply a long history of
diversification within the subgenus Megapomys, with diversification processes that usually involved ecological (habitat and
climate) and geographic (topographic and geological) components. Furthermore, our ongoing studies of other endemic
54
Philippine murid genera on Luzon (Archboldomys, Batomys,
Chrotomys, Musseromys, and Rhynchomys) suggest that these
genera also have undergone extensive diversification. These
patterns and processes will be considered in detail elsewhere
following the necessary taxonomic studies.
Acknowledgments
This study has been made possible by the Philippine
Department of Environment and Natural Resources, which
has provided not only permits but logistical and administrative support. We especially thank the staff of the Protected
Areas and Wildlife Bureau, especially T. M. Lim, A. Manila,
J. DeLeon, M. Mendoza, C. Custodio, and A. Tagtag, for
their continuing encouragement and support. We are grateful
to the Regional Executive Directors and their staffs for
Regions 3, 4-A, and 5, the Cordillera Autonomous Region,
and the National Capital Region for their patience in dealing
with the many permits that they have issued to us.
Funding for this project has been generously provided by
the Barbara A. Brown Fund for Mammal Research, the Ellen
Thorne Smith Fund, and the Marshall Field Fund of the Field
Museum; by the Grainger Foundation and the Negaunee
Foundation; and NSF DEB-0238837, 0454673, and 0841447
to Scott Steppan. Their long-term support is deeply appreciated. The Field Museum, Utah Museum of Natural History,
Conservation International–Philippines, and National Museum of the Philippines have all provided logistical support and
permitted us to pursue our research on Philippine biodiversity,
for which we are deeply grateful.
At the Field Museum, this work would not have been
possible without the hard work, meticulous attention to detail,
and patience of Bill Stanley, Michi Schulenberg, John Phelps,
and Tracy Damitz. The many beautiful illustrations here were
prepared by Lisa Kanellos, Andria Niedzielski, Clara
Richardson, Betty Strack, and Velizar Simeonovski. Tricia
DeCoster has devoted many long hours to preparing data and
conducting analyses, developing maps, and attending to
dozens of details, always with the highest of standards. We
thank Michael Reno and Rebecca Justiniano for assisting with
PCR and sequencing. We thank Richard Thorington and
Jennifer R. Miller for photographing the skull of the holotype
of A. sacobianus. We also thank the staff of the Division of
Mammals at the U.S. National Museum of Natural History,
especially Richard Thorington, Michael Carleton, Linda
Gordon, David Schmidt, and Helen Kafka, for their
hospitality and support over many years, without which this
and many other research projects would not have been
possible. In the field, we have been ably assisted by Joel
Sarmiento, Nonito Antoque, Cardo Buenviaje, and many
others, whose patience, skill, and persistence have been key to
any success that we have achieved. This manuscript has
benefited from thoughtful, detailed reviews of an earlier draft
by Michael Carleton, Guy Musser, Margaret Thayer, and an
anonymous reviewer.
Finally, we offer our most sincere thanks the people in the
many areas where we have conducted our field work, who
have taken us into their homes, fed us, guided us into the
forest, worked hard on our behalf, and kept us from harm.
Their efforts and their friendship have made this project not
only possible but a deep and genuine pleasure.
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in Bayesian phylogenetic inference. http://ceb.csit.fsu.edu/awty
57
Appendix I
Species
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
abrae
aurorae
aurorae
aurorae
aurorae
banahao
banahao
banahao
banahao
banahao
banahao
banahao
banahao
brownorum
brownorum
brownorum
brownorum
brownorum
camiguinensis
camiguinensis
datae
datae
datae
datae
datae
datae
datae
Genus
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
169051
170904
170915
170929
188293
188294
188297
193867
193872
193876
62724
62749
92759
92760
190919
190921
190928
190932
179453
179456
179459
179462
179465
179505
179511
179515
183495
183497
183499
183501
183503
154816
154854
167243
167358
169098
169103
169108
169110
169120
Voucher
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon I/Kalinga Prov.
Luzon/Mountain Prov.
Luzon/Abra Prov.
Luzon/Ilocos Norte Prov.
Luzon/Ilocos Norte Prov.
Luzon/Aurora Prov.
Luzon/Aurora Prov.
Luzon/Aurora Prov.
Luzon/Aurora Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Zambales Prov.
Camiguin
Camiguin
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Island/Province
Balbalan Munic.
Balbalan Munic.
Balbalan Munic., Balbalasang Brgy.: Mapga
Balbalan Munic., Balbalasang Brgy.: Mapga
Mt. Data: 1.0 km N, 1.25 km E south peak
0.4 km N Barlig Munic. Hall
Mt. Data
Massisiat
Mt. Simminublar (Mt. Sicapoo)
Mt. Simminublar (Mt. Sicapoo)
Dingalan Munic.: 2.1 km S, 2.9 km W Mingan
Mt. Banahaw, Brgy. Lalo
Palauig Munic.: Brgy. Salasa: Mt. Tapulao
Mt. Timpoong, 2 km N, 6.5 km W Mahinog
Mt. Timpoong, 2 km N, 6.5 km W Mahinog
Balbalan Munic., Balbalasang: Magdalao
Balbalan Munic., Balbalasang Brgy.: Am-licao
Locality
peak
peak
peak
peak
Location and GenBank accession numbers for sequenced individuals. Brgy., Barangay; Munic., Municipality; Prov., Province.
HM371053
HM371054
HM371055
HM371056
HM371057
HM371059
HM371058
HM371060
HM371061
HM371062
HM371049
HM371050
HM371051
HM371052
HM371035
HM371036
HM371037
HM371038
HM371078
HM371079
HM371080
HM371081
HM371082
HM371083
HM371084
HM371085
HM371086
HM371087
HM371088
HM371089
HM371090
AY324476
AY324477
AY324463
AY324464
HM371064
HM371065
HM371066
HM371067
HM371068
GenBank accession
58
Species
datae
datae
datae
datae
datae
datae
datae
datae
datae
datae
gracilirostris
gracilirostris
hylocoetes
hylocoetes
hylocoetes
insignis
insignis
insignis
insignis
magnus
magnus
magnus
magnus
magnus
magnus
microdon
microdon
microdon
microdon
minganensis
minganensis
minganensis
minganensis
musculus
musculus
sierrae
sierrae
sierrae
sierrae
sierrae
Genus
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
175682
FMNH 175683
FMNH 175708
FMNH 188298
FMNH 188300
FMNH 188305
FMNH 193554
FMNH 193655
FMNH 193877
FMNH 62709
CMNH 646
CMNH 648
FMNH 147871
FMNH 147914
FMNH 148149
FMNH 147911
FMNH 147915
FMNH 147924
FMNH 148160
FMNH 178395
FMNH 178396
FMNH 183569
FMNH 183570
FMNH 183573
FMNH 183574
FMNH 167241
FMNH 167242
USNM 458907
USNM 458919
FMNH 190778
FMNH 190781
FMNH 190782
FMNH 190861
USNM 458925
USNM 458913
FMNH 176562
FMNH 176564
FMNH 176566
FMNH 176568
FMNH 176570
FMNH
Voucher
Locality
HM371069
HM371070
HM371071
HM371072
HM371073
HM371074
HM371075
HM371076
HM371077
HM371063
AY324465
AY324466
AY324467
AY324468
AY324469
AY324470
AY324471
AY324473
AY324472
HM371039
HM371040
HM371041
HM371042
HM371043
HM371044
AY324478
AY324479
AY324480
AY324481
HM371045
HM371046
HM371047
HM371048
AY324482
AY324483
HM370984
HM370985
HM370986
HM370987
HM370988
GenBank accession
Luzon/Kalinga Prov.
Balbalan Munic., Balbalasang Brgy.: Mt. Bali-it
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Mt. Data: 0.1 km E south peak
0.5 km N, 0.5 W Mt. Amuyao peak
1.0 km N, 1.0 km W Mt. Amuyao peak
Mt. Data
Mindoro/Mindoro Oriental Prov.North ridge approach to Mt. Halcon, Hanglo
Mindoro/Mindoro Oriental Prov.North ridge approach to Mt. Halcon, Hanglo
Mindanao/Bukidnon Prov.
Mt. Katanglad range, 16.5 km S, 4 km E Camp Phillips
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Luzon/Quezon Prov.
Tayabas Munic.: Brgy. Lalo: Mt. Banahaw, Idoro
Luzon/Quezon Prov.
Tayabas Munic.: Brgy. Lalo: Mt. Banahaw, Idoro
Luzon/Quezon Prov.
Tayabas Munic.: Brgy. Lalo: Mt. Banahaw, Hasa-an
Luzon/Quezon Prov.
Tayabas Munic.: Brgy. Lalo: Mt. Banahaw, Hasa-an
Luzon/Kalinga Prov.
Luzon/Kalinga Prov.
Luzon/Camarines Sur Prov.
Mt. Isarog
Mt. Isarog
Luzon/Aurora Prov.
Dingalan Munic.: 0.9 km S, 0.3 km W Mingan peak
Luzon/Aurora Prov.
Luzon/Aurora Prov.
Luzon/Aurora Prov.
Mt. Isarog
Mt. Isarog
Luzon/Cagayan Prov.
Gonzaga Munic., Brgy. Magrafil, Mt. Cagua, Sitio Masok
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Island/Province
Continued.
Appendix I
59
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
‘‘sp.
‘‘sp.
‘‘sp.
‘‘sp.
‘‘sp.
‘‘sp. B’’
‘‘sp. F’’
‘‘sp. F’’
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
A/C’’
A/C’’
A/C’’
A/C’’
B’’
sierrae
Apomys
Species
sierrae
sierrae
sierrae
sierrae
sierrae
sierrae
Genus
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
185806
185816
185871
185906
185943
185948
186728
186730
186736
186739
186763
186765
191232
180373
180371
180369
180367
180302
180310
180320
180330
180340
180365
458747
458751
FMNH 135715
FMNH 137024
FMNH 145698
145699
458762
USNM 459844
FMNH 178276
FMNH 178282
FMNH 178288
FMNH 178293
FMNH 178296
USNM
FMNH
USNM
USNM
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
Voucher
Prov.
Prov.
Prov.
Prov.
Prov.
Prov.
Sibuyan/Romblon Prov.
Leyte/Leyte Prov.
Biliran/Leyte Prov.
Negros/Negros Oriental Prov.
Negros/Negros Oriental Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Nueva Vizcaya
Luzon/Nueva Vizcaya
Luzon/Nueva Vizcaya
Luzon/Nueva Vizcaya
Luzon/Nueva Vizcaya
Luzon/Nueva Vizcaya
Palaui/Cagayan Prov.
Luzon/Quirino Prov.
Luzon/Quirino Prov.
Luzon/Quirino Prov.
Luzon/Quirino Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Cagayan Prov.
Luzon/Quirino Prov.
Island/Province
Continued.
Appendix I
Locality
AY324489
AY324474
AY324475
HM371012
HM371013
HM371014
HM371015
HM371016
AY324486
AY324487
AY324484
AY324485
AY324488
HM370999
HM371000
HM371001
HM371002
HM371003
HM371004
HM371005
HM371006
HM371007
HM371008
HM371009
HM371010
HM371011
HM370998
HM370997
HM370996
HM370995
HM370989
HM370990
HM370991
HM370992
HM370993
HM370994
GenBank accession
Penablanca Munic., Brgy. Lapi, Sitio Baua, Mt. Cetaceo
Nagtipunan Munic., Brgy. Matmad, Sitio Mangitagud,
Mungiao Mtns
Mungiao Mtns
Mungiao Mtns
Mungiao Mtns
Mungiao Mtns
3.5 km SW Mt. Cetaceo peak
Quezon Munic., 1.3 km NE Mt. Palali
Quezon Munic., Mt. Palali Peak
Quezon Munic., Mt. Palali Peak
Sta. Ana Munic., Brgy. San Vicente, 4.25 km S of Cape
Engano Lighthouse
3 km N, 17 km W Dumaguete, Mt. Guinsayawan
3 km N, 17 km W Dumaguete, Mt. Guinsayawan
Magdiwang, 4.5 km S, 4 km E; NW slope Mt. Guitinguitin
Magdiwang, 6.75 km S, 4.5 km E; NW slope Mt.
Guitinguitin
10 km N, 4.5 km E Baybay
5 km N, 10 km E Naval
Mt. High Peak, Palauig Munic., Brgy. Salasa
60
Species
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
zambalensis
Genus
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
Apomys
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
FMNH
178297
178310
178327
183348
183393
183395
183405
183407
183414
183530
183532
183535
183537
183539
183604
183610
183617
183618
Voucher
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Luzon/Bataan Prov.
Island/Province
Continued.
Appendix I
0.7 km N, 0.2 km W Mt. Natib Peak
0.1 km N Mt. Natib Peak
Locality
HM371017
HM371018
HM371019
HM371020
HM371021
HM371022
HM371023
HM371024
HM371025
HM371026
HM371027
HM371028
HM371029
HM371030
HM371031
HM371032
HM371033
HM371034
GenBank accession

Ch 1 Apomys - Department of Biological Science

Transcription

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